Many pilgrims were checking about decent accommodation at Pandharpur. Having just returned from the pilgrimage, I thought it to be prudent to share my experience ;
Vedanta / Videocon Bhakta Nivas - Decent and clean accommodation managed by Shri Vitthal Rukmini Mandir Trust. It is located at the walkable distance from the temple. A functional double room with attached (clean) toilet costs Rs. 300 /- per day (24-Hours check-in) whereas AC Room costs Rs. 950 per day. The car parking charges of Rs. 50/- per day extra. The staff is quite helpful. The only draw-back is food. However, there is a veg restaurant located in the proximity called Radheya, which serves delicious food at a reasonable cost (Rs. 70 / 80 per person).
No advance booking is possible and the rooms are allotted on first-come-first-served basis. However, one may phone and request them to keep a room on the day of your reaching the town. There is every possibility that the staff will oblige. The details of the facility can be seen on vitthalrukminimandir.org/images/Vedant1.pdf .
I was personally very happy with the arrangement.