I have cheap racks, they work well for what I use them for.

One bike has a milk crate strapped to the back. It weights a lot, but so does the bike so it's really just another straw on the camels back. It's the most convenient - easy to get things in/out of and it can carry a lot of stuff. I like that I don't have to worry about it getting jacked if I leave it on the bike (I wouldn't leave Ortlieb's unsupervised). The rack is fine, but when I get a big heavy load going (around 12 bottles of beer) the bike get's a bit wobbly. I just take it a bit slow.

My other bike has a rack that it's a little more expensive, but not by much. I didn't feel the need for two milk-crate bikes, so I went to a thrift shop, got a cheap back-pack and fixed it to the rack. I never bother taking it off, it was cheap but it does the job well. If you google "diy panniers" there are lots of suggestions on how to convert messenger bags/back packs. Just make sure there is nothing loose that can get caught in the spokes. When it rains, I pack everything in a plastic bag too make sure nothing gets wet.

It doesn't sound like you're into touring, so there is no reason this has to be expensive.