I think for a good setup, it is going to cost at least $100 or so.
Lots of plants and hiding places is a necessity. I honestly wouldn't bring rocks in from a garden outside, but that's just my opinion.
Cories aren't algae eaters, they are bottom feeders. The eat the extra food that is dropped and of course whatever else you feed them. Otos on the other hand are algae eaters. So, I guess it depends on what you are looking for exactly. Cories are best in shoals of 6, in that case it would over populate a 10 gallon. Otos can live best with a little as 3 together. BUT, they are sensitive to water parameters. I never had a problem with my Otos though, other then they are huge waste producers. Also, keep in mind that some people have trouble putting together a sorority (sometimes they don't work). So, don't get discouraged if it does not work out as planned. I hope that helps! :D