Just got back from SJO after a 5-dayer on a Spirit award at 10K miles RT with their credit card. Their "off-peak" season is only about 30% of the year (heavy in spring and fall) and you have to book well in advance. Packed everything into a rucksack (about half the size of a rolling carry-on) and the bus to/from town was 510 colones (about $1.05). The sign at the departure-tax area at SJO now indicates that credit card charges are run through as cash advances (progress!) and it's $29.