If you like classic aircraft try Bill Lyon’s Custom Classic range, most have float variants. The FS2002 aircraft are now freeware and most work fine in FS2004. His Tiger Moth & Piper cub are classics and include float versions as do many others. You should be able to find his freeware files in the usual places: AVsim.com, flightsim.com et al. The payware files for FS2004 are excellent value at about $12.50

Hope this helps !

Bruce