I love my Smith 1006, but a brick is pricey, because it isn’t a popular cal.
.455 Webley Ammunition is $79/50 rounds when it’s even available. There are enough Webley revolvers floating around to just keep the cartridge in production, but it’s bloody expensive to say the least. There are also “exotic” handgun cartridges like 7.63x25mm Mauser and 7.62x38R which are even harder to get and even more expensive ($100/50rnds), but the only people with Mauser C96s and Nagant M1895s are collectors who only fire the guns once a year anyway. (I’d love a C96 but there’s no way I’m paying $1,500 for a gun that I can’t get ammo for…)
7.62x39 for your AK is going to be about $200 for a case of 1,000 rounds. Used to be less than $100 4 or 5 years ago. 
The most expensive ammo is probably .50 cal, you’re probably looking at at least $2 per round.
RE: Caseless ammo.
Back in the late 60’s, Daisy (yes, the BB gun people) briefly made a caseless .22. The propellant was stuck in a little cake on the back of the bullet. No primer either. The propellant was ignited by a piston forcing air through a tiny hole causing it to heat. A relative of mine had one that I got to shoot a few times. It performed about like any single shot .22; but sales were poor and production ceased. Perhaps its time has come at last.
Description.
Re. caseless ammo: it’s one of those things that sounds like a cool idea at first. The problem is that for semiautomatics and automatics, the case serves another purpose besides simply holding the propellent: it absorbs and then promptly expels from the gun a lot of excess heat. This isn’t an insurmountable problem, but it has limited the caseless ammo concept.
It occurs to me that, using existing airsoft gun technology, it should be reasonably easy to develop a semi-auto repeater using the old Daisy caseless rounds as a base.
Energy from the round itself needn’t be tapped to cycle the action, which simplifies a whole bunch of stuff. A battery-powered motor can work the piston and strip rounds from the magazine, same as in an airsoft. You’d need to use a real gun steel barrel and beef up some parts, but the original Daisies were little more than a slightly redesigned pellet gun anyway.
Main problem to overcome: The propellant cake should be at least a little more durable than the originals.
Secondary problem: Since the thing is largely driven by a motor, it would be trivially easy to convert one to full-auto. Many airsoft models already are from the factory. This ease of conversion to full-auto would cause BATFE to stomp all over such a product with the full might of the federal gummint behind them.
Or you could step up from that piddly little medium-calibre round to something decent like a 4-bore
No idea what the ammor for that would cost but bearing in mind that everything would most likely need to be custom-made by someone with the skill and equipment, I’m betting it would be Double-Plus UnCheap.
As a matter of interest, how long does it take you to prepare and reload a batch of 100 rounds or so, and how much do you value your time at? It’s probably not a big cost component for fairly standard ammo but I can imagine it would become significant if you e.g. need to neck out or otherwise customise a cartridge. Likewise if small batches are being reloaded frequently.
It does take a while in my observation (I do not reload as of yet) but once things get set up and going smoothly it doesn’t take long to run off a thousand or so, which is where the cost savings comes in. You can always put it away for later. A few production runs of different calibers and you’re set for a long time.
Plus reloading can be fun in its own right…
There are commercially made silver bullets. Texas firm.
As per the OP, the cheapest are usually .22’s, with a brick (500) rounds running about 10-15 bucks. The most expensive, off the shelf, probably match grade .50 cal rounds. Friend of mine has a Barrett’s and he told me he got a deal on about 500 rounds for about $800.
As a competitive trap shooter, I can vouch for the price of lead going through the roof. Two years ago a 25lb bag of lead shot was going for about $18, including tax. My club just did a bulk buy and it was $38 a bag, and this was actually down from a high of about $45 three months ago. A case of premium target ammo, on sale used to run about $50 a case (250) rounds, now it’s about $70.
Those are a necessity in lots of areas but you only need a few a year if you know what you are doing. Werewolves are aggressive but there aren’t as many in the wild as everybody thinks. In my 35 years, I have only had to kill 4 and had to threaten only 5 or 6 more. That only amounts to a few boxes of silver ammo bullets and should be affordable to anyone.
Tip: If you happen to be poor and live in a werewolf infested area, you can melt down old jewelry to make affordable bullets.
Will silver-jacketed bullets be as effective as solid silver? That’d save me some money. Although, as mentioned, it’s usually only a couple of bullets a year. It does add up over time, though.
A-square ammo sells .600 Nitro for $20 a round and .700 for around $17.50 (somehow) but if you can afford a rifle like that, the ammo costs are the least of your worries. I have a feeling that one shot from a monster like that would be plenty of range time for a while.
I pay about $3.50/round for .50 BMG ball (mainly Talon). Match runs about twice that.
Not as effective. I don’t think you’d want to take that chance, Bob. Lycanthropy is a hell of a disease.