2 things:

1. CVS stores ARE linked by a central database. Any CVS store can see ANY prescription you have filled at ANY CVS store and you can have that prescription filled at ANY other CVS. You just have to say that you have not been to that particular CVS but you have prescriptions filled at a different one. Problem solved.

2. CVS price matches! ANY price. $4 prescriptions, done. They just have to call the competitor pharmacy to confirm the price and that's it. They also accept competitor coupons as long as they're not expired, and some stores will even give you more after that coupon.