Another excellent "Slosher" is the Summitek Cradle.

http://www.summitek.com/cradle.html

I have the 4x5 version and the 5x7 version and I like them very much. The CR45 holds 6 sheets of 4X5 film, fits an 11X14 tray and costs $45 + shipping. The CR57 holds 6 sheets of 5X7 film, and fits a 16X20 tray and costs $55 + shipping.

Summitek does not make an 8x10 version of the Cradle. I have the PF 8x10 Slosher. It is very similar to the Summitek design but is more expensive.