I would suggest a pair of powered pa cabs, wharfedale evp x12 or similar (http://www.reverb-store.co.uk/product-detail.asp?prod=1106) around £400, a lowend mixer ( [url="http://www.dolphinmusic.co.uk/product/8540-behringer-xenyx-1202fx.html/?utm_source=google&utm_medium=shopping&utm_campaign=base"]http://www.dolphinmusic.co.uk/product/8540...m_campaign=base[/url] ) 12 input with built in effects about £100. sell on your peavey cabs to fund a small power amp to run your existing monitors.
this will enable you to upgrade your pa by adding powerd bass bins etc as gigs and venues get bigger, and when funds allow invest in a quality desk. The beheringer mixers have always been ok in my experience.....but think of it as disposable.
when choosing pa I learnt that in 12 months time it aint gonna be loud enough!!!
Thats the route I would go if that helps. Gear linked to is just as an example.
Richard