I worked for a company that used a hot melt crack sealer called the Marathon. Seemed like a pretty productive piece of equipment. Between $1-2 Grand I believe. It was like a kettle on thin metal wheels and had the reg. size propane tank. Held 2-3 blocks of material. Pretty compact in size. If I ever decided to go into the business I'd start off with one of those. Anyone use them? Any problems after repeated use?