I really think there are several overlapping concerns here, all with trade offs.
Yes, a Biax scraper can get VERY expensive. I got my ancient one from Ulma Doctor for an extremely fair price. On eBay, most sellers are not as nice as Mike is, to say the least... So one approach is to simply wait for a good deal to come along. I do this a lot, but I notice that most of us get on a kick and want to be running with it NOW! Damn the cost and learning the options and the market! Often, mistakes are made, some expensive. I try hard not to do that.
One regularly seen approach is to show the ba$tards that one can be made for next to nothing using stuff laying around in dumpsters or modding a HF tool. Good idea, can allow for quick prototype builds with little investment of time and money. The down side is that quick and dirty does not usually give us the elegant 'does everything exactly the way I want it to and will last forever' qualities that we would also like to see. Been there, done that. Quick and dirty can require multiple resets, starting over from scratch again. After a few tries, the project is often abandoned.
Another common approach is trying to build the PERFECT power scraper, with all the bells and whistles, NASA grade components, ergonomic studies, pretty CAD drawings, finite element analysis (FEA), torture testing to failure, built in floodlights, video camera, electronic leveling readouts -- well, you get the idea. It will never be finished, and will cost many times more than a new Biax by the time it is only partially functional and is abandoned. Been there, done that, too...
All this is to say that I think we need to strive for a simpler and better answer. The more people working on it, and posting their success and failures, the better. In a tiny niche market like this, we need to create any improvements to the craft, because industry does not give a damn about us, no money to be made. Work on it, keep working on it, and let us know how you are doing, and what works and what does not. Collaboration is a powerful tool...
