If you just have one BP then the cost to build/buy a mouse breeding setup will be more expensive than just buying a single mouse each week, and probably more work than it's worth. Also remember that your BP will only be on mice for a short time, so you will either need to slightly modify your breeding setup to accommodate the size difference between a rat and mouse. Now if you are planning on getting more snakes than breeding feeder rodents could be a great idea. So if you have no problem with the added work it takes to breed rodents then by all means look more in to it and start breeding. I just recently started breeding feeder rats for my snakes and food costs are way lower and not to mention I think it's super fun to do. Have fun with you new snake