Well to me the M-21 is unresaleble, if there is a 50+ m21 coming into the country and if say 10 guys are selling them at once, then the price is going to plummet and I'd still have to spend another 600+ for an Eotech, if they drop the m21 and drop say 600 from the tavor, that would make it reasonable, and at this time, to me, it seems IWI is trying to get rid of excess m21 stock, and that they are bundling it with a very superior rifle, to clean them out at a high price.
And from the photo above, it seems that the Eotech is mountable on the tavor, at least in terms of dimension with the m21.