Sympathies for the loss of your dog...and congratulations on your new python!

Balls love their hides...all of mine sure do anyways. Only my Boa hates his...he'd rather bury himself in his bedding, lol.

Even Petco/Petsmart sells live mice, although it's at a rather high "pet mouse" price. But with only one snake to feed, it wouldn't make a huge difference - maybe $5-7 extra per month.
Not PetSMART. I mean yeah they sell live mice but if you go in and get one every week the associates will begin to recognise you and begin to suspect you are using them as feeders, and they will likely begin to deny the sale. PetSMART does not intentionally sell live feeder mice.

Have you considered ordering in bulk online? Some places like Rodentpro and Mouse Factory sell frozen feeders at really reasonable prices. That way you can stock up!