Since you already have a sewing machine, you may want to consider an embroidery only machine. That's what I did. For about $600 you can get Brother PE-770 that has a 5x7 hoop - it's a great little starter embroidery machine with a decent hoop size. If you wanted a Brother combo machine, you'd have to go up to the 1250d to get that hoop size. The 950d is a great little combo machine, but it is around $700-$800 on sale or with trade, and only has a 4x4 Hoop. The lowest priced Brother combo is the non-Disney SE-400 (or LB-6800-PRW) for under $500 but again only a 4x4 Hoop area. Dealers may have refurbished or used versions or classroom machines for a bit less.
Again, the biggest bang for your buck for a starter/beginner is the Brother PE-700 stand alone Embroidery only machine. I love mine!