Be sure that you have the necessary permit to stock your water (the former owner may have had one). You can request the application to stock yuour water from your local WDFW region office or headquarters.

I would stay away from planting the bass. They reproduce easily and nearly always over population small ponds. The rainbows would need some flowing water for any attempt at spawning and a significant size stream for success of the rainbows.

If you are looking to plant the pond the cheapest buy smaller (3/4 inch) fingerlings and grow them to catchable size in the pond. At a couple hundred fish/acre you could expect them to get to 12 to 14 inches in about a year. The other advantage of using the smaller fish is that as they grow out their fins are generally better formed. They will grow faster and you can plant a few more if you are going to feed the fish.

If you want instant success you cn buy fish any size you want including fish well in excess of 10#.

Tight lines
S malma