2 nights in ColesBay/Freycinet area and 1 night in St Helen's/Coast area. Of course cheaper would be better, but comfort is impt too. So a B&B?

Going in less than 1 month!

These don't come under the heading of cheap but you might want to check these places out anyway. They come from the B&B guidebook I use.
www.piermont.com.au for Swansea which isn't far from Freycinet.
www.edgeofthebay.com.au for Freycinet
www.freycinetlodge.com.au for Freycinet
www.vision.net.au/~warrawee/ for St. Helens

We stayed at Big4 holiday park at Coles Bay (Illuka) and rented a two bedroom cabin. Was good for the money about $70. Very central.

We also stayed in a cabin at Bicheno but did not like it at all. Very small and felt like staying in a parking lot. Though I enjoyed Bicheno itself.

Also we stayed at night at Scamander Bay (didn't quite make St Helens that night) at the Chancellor Inn. A bit old and tired but clean and what a view!! About $75/pn. Gorgeous place.

We have stayed at lots of budget type accommodation in Tasmania and all very clean and comfortable just some needed some maintainance work.

I suggest that the post from "nickyms" be ignored. This poster has only recently appeared on Fodors and all of his/her posts are devoted solely to promoting the merits of an apartment booking service. In other words, this appears to be straight advertising. No need to contact the Fodors editors, I've done that.

Not sure why you'd miss a stay at Waldheim huts in the Cradle Mountain National Park. Simply one of the most amazing travel experiences! Can you fit a night or two in there? It's a fabulous place and even if the Waldheim huts are fully booked then Cradle Mountain Lodge is good too. We've stayed at both and prefer Waldheim for its unique ambience. Good luck!