Yes I would make it plug and play - just let me know how long you want to mains wire and wire for the switch ... that's about it. I would make it so that all you need to do is connect two wires to a terminal block. I'm not really sure how much I want for it - an equivalent transformer is £95 plus vat new at Farnell, but one that would be sufficient for your two steppers is £31 (at rapid electronics) plus a few quid for the capacitors, rectifier, switch. It will be £6 to post mine.