A few people have been scammed on the site, Only use paypal to pay for items for sale by other members. If they will not use paypal, its likely a scam NEVER SEND E-TRANSFERS OF ANY KIND.
This is what I use but I'm stuck in an apartment until my house sells in Illinois. It has an auto shutoff feature which has been pretty accurate. The first few times I used it I was nervous I would blow a tire.
I have one of the mini Slime pumps for travel on the bike. It's not super fast, but will air a tire and takes up very little room in your frunk/trunk/etc.
If you're changing tires, you'll want a compressor with a tank because you need a lot of air to seat the bead on a tire once it's mounted. You could possibly get away with a smaller compressor if you run a ratchet strap around the circumference of the tire and force the bead against the rim, but I've never actually tried this because I've always had a proper shop compressor.