the badger disposal is the base model of ISE BRAND, one of the top brands on the market. i dont normaly recomend the badger model but if that is what you want to install it should not be too hard. first of all, all the ISE disposals use the same head assembly (the part in the sink) so if you are installing a $49.00 or a $200.00 disposal they are the same head assembly.
so if yours is still in good shape you can leave it in the sink. and really that is the hard part of the job. if you stay with the badger model the drains have a better chance of lining up also. as far as what it would cost, i dont know what that type of job goes for in your area. we charge $65.00. Note: if you are hooking up a dishwasher to it, you have to knock out the little plug before you hook the hose to it.