Welcome, Al. I live in Saco. I get compost by the truckload from DuBois Topsoil, I think they are in Dayton. They sell that shellfish compost at a much more reasonable rate than anyone else around here, and their delivery rate is far less as compared to a nursery that is 1/4 mile down the road from me. As far as mulch, if you need more than bags (i.e., truckload), call around and compare prices from the suppliers closest to you. If you have to pay a delivery fee, distance matters. I'm not sure if Dubois sells mulch.

De-mulch the roses, as in you piled mulch on top of them for winter protection? It can be definitely be removed now.

Hello Al & Bea;
I am also in Saco and bought top soil from Bayley's Elk Farm in Scarborough last fall. It was some of the best dirt I had seen in a long time and reasonably priced. Depending on where you are in Buxton, that could be an option.
The Saco transfer station is offering compost but you have to pick it up and I am not sure if you need to be a resident but they were charging residents $ 3 a cubic yard.
My favorite nursery/farm stand is in your town, Snell's. They are on Route 112 just north of Route 4A and are the nicest people. They will give you plenty of advice and it never costs.
Welcome to Maine.
diene