As above, depreciation is tiny enough you can ignore it. Drive 5mph slower and you’ll save that much in gas money over the 5 months.
The three major factors in your roundtrip cost of ownership are where & how well you buy/sell it, the taxes/registration, and unexpected maintenance.
Buy/Sell:
If you buy from a dealer and sell to a private party, you’ll pay too much and sell too cheap. So buy from a private party. And negotiate like hell.
Selling to a PP is better than selling to a used car lot, but about equal to what you might get as a trade-in on a new car, although that introduces a host of variables as the amount of the trade-in is strongly coupled to how aggressively you worked the price of the new car.
Wherever & however you sell, negotiate like hell. You might even sell it for more than you paid for it *if *you’re better at this than whoever you buy from & sell to.
Also better to buy in a low cost area and sell in a higher cost area. I live at the far edge of suburbia and driving 50 miles out into the sticks I can often buy 5+ yearold genericmobiles for a couple hundred less than I could sell them for in inner suburbia. The volume wouldn’t support a real arbitrage business, but the difference is enough to matter on a single purchase.
Also, if there is a distressed area nearby, say, where a big factory just closed, you can snag some extra good deals there from desparate people. And again, when it’s time to sell, don’t sell there.
Taxes / Registraion:
If I was looking to own it for only 5 months I probably wouldn’t bother re-registering it if a) the plates weren’t going to expire in that interval; and b) I lived in a jurisdiction where the plates stay with the vehicle, not with the seller. That’ll save some significant money.
Although depending on how agressive the local DMV & police are, you might be running some risk of getting caught. 30 years ago this was done all the time. Nowadays I just don’t know if detection is 100% certain, a coin-flip, or no chance in hell. In my current jurisdiction the plates stay with the seller, so I can’t test the local enforcement quality.
Unexpected maintenance:
Don’t have any. Easier said than done.
But going for bottom dollar on the buy-in is probably setting up to have an ugly surprise. *If *you have the cash, better to park $5K in the car for 6 months & get it all back on sale than to park $3K in the purchase and then be faced with either a total writeoff or a $1000 new transmission halfway through your ownership.
For your fixed $5000 budget, that translates into buying a better condition low end car versus a worse condition higher model. But avoid Yugos no matter how good the condition.