well first dont buy drivers used! you never know what your going to get, its just my 2 cents and a few others but RF fell off the map, they were "IT" in the early 90's but have not kept up. and sony subs have always been the bottom of okkkkkk for me any way, if your looking for entry level good stuff or the "best bang for the buck" id look into kicker, eclipse, some aplines might be in your ball park, alot of people like mb quarts i dont really, but there all in the same group.
as far as amps go again use the names mentioned above, and alot of manufacturers, make one good thing but not another, like a poineer or sony (non explode) HU is ok in my book if your looking for something base line and cheep. but thats the only thing "I" my self would use. but its your $$$ and we can help even if we dont like what your picking from we will tell you the best of what you can afford