Any suggestions on coolest running monoblocks?

I'd go for a pair of Channel Islands D-200 monoblock amps, fits your description and budget perfectly.
30 day money back guarantee, call Dusty, you won't be sorry.

The new Rowland 201's are a pair I can think of.

I second Rx8man's recommendation. My Channel Islands D-100s replaced a pair of Antique Sound Labs 1009 (parallel 845)tube monoblocks driving Vandersteen Model Five speakers. I was able to compare the D-100s to the NuForce Ref8s. In my system, the D-100s were a better choice.

Dusty has struck the perfect balance between solid state (control, frequency extension) and tube (imaging, holographic mids) topologies. Highly recommended!

Do you need monoblocks? I was really impressed with the Spectron Digital One amp when I owned it. There also happens to be one for sale now on Agon [please note that I am not acquainted with the seller, nor do I receive any remuneration for this post].