There are a few things to consider here, the first being what kind of flying are you going to want for these engines? This is somewhat important to know because different classes of planes have different weights, and dimensions, which require a different engine.
You mentioned about 80-90"s or so, and under 20lbs...that might put you into an unlimited aerobatic class of plane, in the 25%-30% size range...in which case you'd be looking at lightweight engines in the 40cc-60cc range.
These are very popular sizes, and for good reason because they are affordable without costing as much as your car, and they can generally be hauled around with anything as small as a small truck.
I've had very good experience with BME myself, as well there are other very nice engines..IE Taurus, ZDZ, Brison, DesertAircraft, 3W, etc.. . As usual with anything, the more money spent, the better, although the high end engines are mostly very equal in performance and value...there are others to consider as well. I will say though, they aren't cheap,,,ranging in price anywhere from $500 to maybe $700 with everything...a few exceptions here, but plan on about $600++ for an engine budget for some of the engines I've mentioned.
If it's Scale flying you want, the engines still are pricey, up around $350-$450, but because they are not the lightweight performance type, and don't have electronic ignitions and such, they are a bit heavier, and not quite the power of the high end units. Some modelers just don't need all that, and for good reason...scale effect, and the less powerful heavier engines are a bit cheaper. Not taking anything away from them at all, it's just different application is all.
Just do some homework in here, and any info that you find on engines, bookmark, or subscribe to the thread and you will get updates on that thread.
All of the gassers are powerful, and for the most part, easier to run then glow...not to mention CHEAPER to run. It's a fun way to grow in the hobby....so just keep your eyes out, and check the engines forum frequently.
