If your reasons for wanting to use biscuits, is because you think it will make it stronger. No, that's not what they are for, they do not add much strength at all. They are primarily used to help line up, and hold something when clamped in the proper position while the glue drys. You can certainly make it without biscuits, it will just be a bit harder to clamp it up, and still hold the pieces in position without moving. As mentioned, you could also use dowels, a simple dowel jig is far cheaper than a biscuit cutter. Pocket holes may work also, but probably are also not be the best way to go. Renting a brad nailer might be a option, loosely clamp it up with glue, line it all up, tighten up the clamps and zap some brad nails in it to hold it in proper position while the glue drys. Actually, a really good tool rental store may even have biscuit cutters available for rent.