Hey everyone well..............im thinking of doing a sump now becasue i have to much equipment hanging in the bak of my tank!!!!

an i would like to build the rock work up in places so i need to get the equipment out of here. S
So my friend has a 20 gallon sump i was wondering if that would be a good sump for my 75 gallon he said its an oceanic.........dont know if thats good or not, but if i decide to get it and its good for my tank what should i look for in price......like what would be a rediulous price for that and what would be reasonable
thanks