I don't know how anyone would plan to use barber's shears on themselves. Go with the clipper with a comb attachment on it. Or find a Flowbee at a garage sale.
I've purchased professional shears on ebay on the cheap for a stylist friend. Forged Hitachi steel convex edge shears will easily run you over $200 new, and they come in many varieties, so it's not a one size fits all. There's straight, semi and full offset, twisted thumb, swivel thumb, and different lengths of each, all with or without finger rests.