How much should it cost to replace transmission?

alright so a seal went on my 1990 honda accords 5 speed transmission and all the gear lube leaked out resulting in total failure of the transmission even ripped a 3 inch long gash in the case. now the only transmission shop in my town said that if i get a used transmission he'll put a new clutch, pressure plate, etc. in it and put it on the car for 500 is this about what i should be paying or should i look around at other shops near my area.. also I enjoy working on my car myself and have replaced and worked on just about everything under the hood expect for doing anything to the block or head.. so i feel comfortable working on my car just haven't ever touched the transmission so also would this be a job someone with my experience could be able to do aslong as i use my trusty repair manual.. i'd love to go this route since it would be cheaper and i would know that only the best parts are being used. thanks for any input on this question!