The street food is plentiful and good. Different areas of the city have their own specialty. On the road from the Swiss Belhotel to the city are BBQ seafood stalls. The eastern most main street of the city has a large number of satay chicken stalls (although satay stalls are pretty much everywhere) and on one of the cross roads between the two main streets are noodle soup vendors.
The most expensive street food will costs you less than RP 40,000.