How much of a difference can an expensive camera lens make?

I’ve had photography as a hobby on/off for over 30 years, and almost entirely using Canon equipment; I just got my first two Canon “L” lenses (100mm macro and 100-400mm zoom), and there IS a difference in contrast and bokeh. Whether that difference is worth the extra $500-1000 is probably an individual determination.

I may have over-reached on the 100-400; it is a great lens, and I read hundreds of glowing reviews before buying that included the word “heavy”, but I ignored that bit, and now having second thoughts. I might try to trade it out for a 70-300 L.

The Nokia Lumia is one of the best camera phones on the market.
Get your wife a nifty fifty.

This is an inexpensive fixed focus lens. (it’s not a telephoto or ‘zoom’ lens) It’s very fast, it will open up to 1.8. It’s inexpensive. It really gives you a lot of bang for the buck.

Not fixed focus, fixed focal length (or “prime”).

Not a bad lens if you have nothing but not sure I’d spend $110 on it if I already had an 18-55 3.5-5.6. Good if you shoot in lower light or need really tight depth of field.

I know, but a 30mm lens intended for a 35mm camera has an 35mm effective focal length of 46-48mm on a APS-C DSLR so in terms of the field of view at least, it’s more or less the same.

My point was that if you want something similar to a 50mm prime on a APS-C lens, about the only option these days is around a 30mm focal length, and there aren’t many of those, with the Sigma being one of the best.

A local camera shop here rents lenses (Seattle area). If going on a trip or having some other rare photo needs, it lets you cheaply rent a niche professional lens that otherwise would be a ridiculous amateur purchase. It can be a great $50 well-spent for a week of fun shooting.

FWIW to your wife, under advice I got on here I picked up this lens from BH Photo:
http://www.bhphotovideo.com/c/product/740781-REF/Canon_0345B005AA_EF_70_300mm_f_4_5_6_IS.html

refurbished for $600. ZOMG. The zoom on it is excellent excellent (and I do a lot of wildlife photography) and the photos are gorgeous. Easy to use, fantastic lens and I thought the price was great. I have access to my boyfriends $2000+ super zoom lens and I never use it, I only use the one I bought from BH. Love love love. They have a great return policy too if she gets something and it isn’t exactly what she was looking for.