you really need to research what different torts require and how large you want your tort to be. There are some that are 6 inches and then thare are some (sulcata/spur thigh) that could be 2-3 feet and a hundred pounds or so at adulthood. Also, different torts have different requirements. If you are in the city, I would suggest you getting a russian tortoise. They stay smaller and are full of personality. I have often seen some listed on craigslist. There is also a long island turtle/tortoise rescue (i think thats the name-you could google it). Make sure you are ready for your tort first with basking lights, uv, food etc. before you acquire one. You don't want them to get sick.
i already have basking light, uvb5, CERAMIC INFRARED HEAT EMITTER, heat pad, and a humitdifiter.also three different band name tort food. russian and greek is good for me, and i have a back yard. they can stay in there during summer
try checking the local animal shelters as well as local classified ads. you could also try posting a wanted in our Wanted Forum
you're going to want to use manufactured foods very seldom. try to feed fresh greens and weeds - which types will vary depending on the type of tortoise you adopt. do plenty of research and you should be in good shape!