And if you have cash (US will do) Maya are currently giving 20%-25% off. Once you're at Customs (there will be a queue) it's generally quite quick - 2 or 3 minutes maybe - though I've never had a bag opened.
Cabs are reliable and will take maybe 25 minutes. There's a fixed fare that's quite a lot - don't know what it is these days. But why don't you email Maya and ask them what their current cash fare is from BZE to SP? Personally I wouldn't bother to try to save a few dollars, at a cost of a lot of time.