There are numerous FX5s on CL for $140-175
And another is selling a 90G setup with an FX6 for $300 you could easily take the filter and get $150 for everything else.
Sump can be an option pet supplies plus not sure if you have one around is having a gallon per Dollar sale. Get a 55 gallon and do a diy sump. Should cost less than 80 dollars everything brand new and built.