I have to go with choclatechef for the most part. Hobart makes commercial kitchen equipment and KitchenAid was their home line - when they sold the KitchenAid line to Whirlpool back in the 1980's the quality went down. Sometime in the 1990's either Whirlpool changed the specs, or some of their suppliers did, and they had a bunch of units that failed within the first year warranty period ... whatever got changed that went bad seems to have been resolved.
My problem with buying anything on eBay is that I'm not a big eBay fan because you never know how honest the seller is. Sometimes you get what you paid for, sometimes you don't, and you never get a warranty. And, you still have to "win" the bid - which can be harder to do than you think sometimes.
If you're shopping for a Whirlpool KA on a budget, and color doesn't matter, check out the refurbished units on Amazon.com. They are mostly white - and are units that broke during the warranty period. The good thing is - what was going to break was replaced ... and they usually don't have any more problems. They are also a great bargain!
Other places to check would be
www.qvc.com ,
www.cooking.com , and
www.chefscatalog.com ... and just compare prices, shipping & handling .. etc. Same goes as to resources for attachments.
As for a suggestion on the mixer - either the 5-qt Artisan (tilt-head) or 5/6 qt Pro (bowl-lift) model. I wouldn't waste the money on anything with a smaller capacity or less than 325-watts of power (like the bottom of the line things they sell at Wal-Mart).
As for suggestions on attachments .... the grinder for sure, and if he likes to make sausages the sausage attachment that goes on the food grinder for sure. If you Dad doesn't have a food processor - the slicer/shredder attachment would probably be a good idea. The fruit/vege strainer attachment has so many "don'ts" that it was a waste of my money - I've got a strainer and wooden spoon that are quicker and just as easy to use, don't have the restrictions, and were $45 cheaper. I'm also not to impressed with the pasta plate attachment that goes on the food grinder to make a pasta extruder - you're limited to soft egg noodles.
Now the pasta roller attachment is a little more practical if you like to make your own homemade pasta ... and works great ... but you are limited to a wide flat sheet (for ravioli, lasagna, or hand cut noodles like pappardelle), and cutters for linguine and fettucine. If I had it to do over again, for making pasta, I would buy an Imperia pasta machine, the electric motor, and would have the ability to buy even more cutters for about $15-$25. In the longrun - the motorized Imperia cost a couple of bucks less than the KA pasta roller set, and with additional cutters can do more.