The 750X is currently $124.99 with an additional 20% off and the 500X is $99.99 with an additional 20% off. Both include free shipping. I'm going with the 750X.
I have tried ordering a Drill Dr. from Amazon twice in the past, both times they were on sale for a really good price. Both times, I received an email stating the items were on backorder. Also, both times after waiting weeks, I got another email stating they were not able to get the unit at the price they posted. Needless to say, I still don't have a Drill Dr. I won't be ordering anything from Amazon anytime soon either.
Good luck to those that get in on the deal, and actually get one shipped to them. I don't have much luck at times!
Personally I wouldn't spend that much on this tool but I did find a refurbished Drill Doctor 400 kit on Amazon a few months ago and my final delivered price (after a rebate from Drill Doctor) was about $45.
I've already used it once after the first hole I drilled in some steel took a lot of "wiggling" with my TDK. I then broke out the DD and sharpened the bit in seconds and the rest of the holes went right through. IMO a very sharp bit is really needed when using a portable drill to drill steel because you just dont have the RPM.
So IMO if you can pick one up, new or refurbished for $75 or less delivered then I think it is a worthwile purchase. Check Ebay. You dont need the latest and greatest version and probably don't even need the versions which have the 3/4" chuck since 1/2" is good enough for most of us.
And don't worry about parts if you buy an obsolete model. Drill Doctor Parts
Drill Doctor has a $15 rebate on the 750 and 500 if purchased by April 30th and submitted by May 15th. That would lower the 500 to approximately $65 after rebate if you also get the Amazon 20% discount.
Drill Doctor won't do brad points. I sharpen my brad points with a fine flat diamond file on the inside of the cutting edge. Only takes seconds. Or on larger ones, my 1" belt sander does is great.
Nevertheless, I really like having the Drill Doctor. Handy-handy item.