Help with Amplifier

Recently bought one of these 300w speakers:

http://saveltd.co.uk/peavey-messenger-pro15-mkii-8-ohm-passive-pa-speaker-pro-15-mk2--5-yr-warranty-1549-p.asp

I am unsure of where i can find a cheap option for an amplifier that will just power the one speaker. How cheap can i go? any ideas?