Making a list of must have stuff, that includes a water heater, how do you heat yours, OK, a budget of $300, extra points for cheaper, probably be used more for making coffee! Make, model, fuel used, why you use it.
primus.us

Advocate II
bought this one years back and works pretty good. also bought a similar unit of the "Gasland" brand and it is also pretty good. uses 2 "D" batteries to ignite the burner and I use a small 12vdc pump to supply it from a Jerry can. if you cut back on the flow, it will get hot enough to scald, so it is a serious water heater. does very well on fuel and I've gotten weeks on a 5 pound propane tank
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