Please, take whatever tent you think suits your needs best. If one of your needs is not to spend more than $20 on a tent, then that qualifies as much as any other need.

More expensive tents generally have better materials and will hold up better under stress, strain and weather. Since a tent that collapses, leaks or breaks a pole is pretty much a useless dead weight, most folks here would rather spend more and have something sturdier.

However, it is entirely possible to backpack with no tent at all, or with a 3 mill plastic tarp, or any number of cheap alternatives -- and be happy, so it really does come down to finding your own way of getting out there, that satisfies your idea of the right way for you.