Owenhouse, Murdoch's, etc. all sell bagged organic soil. They typically have spring specials and rebates, so keep an eye out right now. Western Conservation Services out of Belgrade sells it by the truckload, not sure about smaller quantities. Of course, only you can judge what is "affordable". If money is tight and you would like some healthy exercise :) dig down your pathways around the bed and fill the bed with the excavated soil. Then fill the paths with straw, leaves, etc., whatever you can find to keep your feet out of the mud. People frequently give away straw in the Free section of the Chronicle. Good luck!
How deep is your raised bed? Does it really need to be "organic"? If you want to create a growing medium maybe you want a mix of topsoil, sand, and peat moss. (Ask a nurseryman.) What happened to the soil that was there when you dug the raised bed? I live out beyond Belgrade so I am not familiar with sources in the Bozeman area.
AK & S has top soil and compost for sale at $20/yard (price - the last I heard) They are located west of Belgrade on the Frontage Road in Central Park. Half way between Belgrade and Manhattan. The phone number is 284-4148. We have used their products and have had no problems. Soil has no rock or clods, he runs it through a screen.
Amber-I wondered where people would get the soil to fill their raised beds. Is there any place in your yard you could dig up some soil, this would be the cheapest way to start and then amend with manure-usually free; compost from your pile and as per the leaf idea above. I think to buy organic material is pricey; most garden stores have organic compost in bags or some as bulk; if you only need one or 2 bags per box this hopefully wouldn't be too expensive. Good luck and let us all know if you find this affordable ORGANIC soil.
Thank you every one!
~No it doesn't have to be organic~We have terrible soil in our yard, and no where else to dig ;-)
~Our compost is not ready yet~ we do not have a truck to haul soil~I am going to call Ak&S & Western Conservation soils & let you all know what I find! ~ Thank you all again!!!~Amber