i went to my local air place, and tank rental is $55 a year plus $20 to fill. is this unreasonable? i asked if i could buy a tank, and all they had was 20lb for $180. i found some 5lb on ebay for around $65 is this a good price, or should i look somewhere else. i could make a trip to oklahoma city if anyone knows of a place that would be cheap there.