RE: PROFI RAMBLER .049
Dave, it's been at least a year or two since I heard, but Foras were $150ish...but I'm not sure if that includes the spanner wrench that also has a glow socket on a swivel. You could easily make your own spanner for unscrewing the head and backplate.
If you plan on getting a lot of use out of these engines, then I think they're worth it. In the same time frame that I owned my Fora, [about 7 years]...the engine ended up costing me about $20 or so per year and it was still in great shape when I traded it away for an engine that was worth about $70. So it really worked out to more like $10 per year spread out over 7 years.
My 1st Cyclon was a different story...I lost that sucker in a shallow "swamp" only 100-200 feet from where I was standing. It sounded like the shaft seized up and it tore the firewall out while the plane was just cruising along. That happened in the 1st or 2nd year of ownership so that was a bitter pill to swallow.