Brad,
I can't really comment on the PL5/Merlin as I have no direct experience with the combo, but I can say that the speakers don't require a ton of power to work well. I've gotten more than adequate SPL and very good dynamics out of the older VSM SE (in a medium sized room) when powered by Cary 300b monos, which produce +/-15wpc. On that basis, I'd speculate that power output from the PL5 would not be an issue unless your room is large and/or you want pretty high SPL.
As to price, used VSMs of various pedigree are usually listed here between $2.5K and $4.5k. Older variations of the VSM can generally be upgraded. If you find a pair that looks appealing, Bobby P. of Merlin is always eager to work thru that with you. If you like the particular VSM "family sound" (not everyone does, but I'm a big fan), I'm pretty confident that you can get a good example well within your budget.
Good Luck,
Marty