There are several formic acid dispensers in the market, but they don't seem to be very popular. There may be several reasons for that, including that beekeepers are not to keen to be playing with formic acid and release of formic acid varies with weather.
What I haven't seen in the market is oxalic acid dispensers that allow for a long-term applicaton of oxalic acid over a period of 4-6 weeks (not talking about the one-off vaporisers where one needs to come back weekly unless the hive is going through broodless period). Would a long-term treatment of oxalic acid delivered with a