Kizuna and Ninja Masters certainly aren't as refined as the KoF or Real Bout series, but by no stretch of the imagination are they "shit SORRY." Kizuna is GREAT fun IMO, offering some Real Bout'esque combos and very fast game play. The tag feature is, of course, an exciting element too. I like most of the characters too. It was a recent discivery for me on MVS and I am glad I have found it. Pretty decently animated for it's age as well.
Ninja Masters is also really cool. The combo system is slightly more Killer Instinct than KoF, but fun none the less. The characters are a little smaller, but that kind of thing has never bothered me. To be honest, I never even noticed the size of MOTW characters as small either. That's just the way they are, y'know? While I don't have a lot of time with Ninja Masters, what play I have had has been fun.
Are they worth $2500 and $1200 respectively? Well, no, I wouldn't pay that. As $40 MVS carts, you damn betcha'.