Witsend makes an excellent point here, if you have older vehicles, get a great price, and only expect a few years out of it's worth it. I bought my 2nd one from harbor freight back in may on mothers day because of their 30 % discount off the $1099 price. I did it because the total was only a couple hundred over the cost of a years updates on my old DS708, and the new one has a year of updates. If I can get one good ford update I'll be satisfied. I'd love to have gotten the MS906TS but it just wasn't worth it to me compared to the DS708. I dug deep into it and you actually come out better in several ways getting the plain 906 and the TS601 separately.
So, if you can afford it, get the 906, it's actually the replacement for 708.