Some general comments / thoughts to hopefully help the OP...
Blades are probably not "rare" but I wouldn't characterize them as "common" either. The factory blade setup is very unusual. The blade is detachable but the main framework attaches to the front axle. Then there is what I'll call a "support frame" behind the front axle. That has a plastic block which rides in a channel with it's own framework welded to the machine's main frame. The idea is that the force acting on the blade is (eventually) transferred to the main snowcat frame. When you turn the steering wheel on a regular truck with a snowplow, the plow stays oriented with the truck. But on this Tucker design the plow turns with the front axle.
The whole system is quite involved. If I were shopping for a used Tucker and wanted a blade I would not recommend the idea of buying one without and adding a blade later (even if you could find one for sale). In addition to the blade you have a six-way valve in the cab. The hydraulic system has some differences as the hydraulic reservoir is slightly larger and there's a fluid cooler installed in front of the radiator. I'm quite sure the hydraulic pump's output is greater as well.
The blade itself is a six-way blade: power up and down, power angle left and right and tilt seven degrees from level side-to-side. The width is eight feet and there are two nine inch bolt-on extensions giving a total width of 9 1/2'. Several years ago in a conversation with a factory Tucker salesman I was told the option price (in the 1980's) was probably $10K. And it added about $3K to the price of a used machine of that vintage.
As far as this machine (for reference I owned a 1980 1543 with front blade (bought from Sno Trans)):
I'm not certain when Tucker started offering the rubber belt and steel grouser track system. I think it was in the mid-seventies. If you look carefully at the right front track idler wheels you'll see the rear wheel (a de-icer wheel) looks slightly different. It's "tire" is thicker. The wheel casting is slightly smaller in diameter. (Look at these idler wheels and some of the others on other Tuckers on Sno Trans web site). I think these thinner wheels were sourced by Tucker and used in early production models. Later on they went to the style like the de-icer wheel. That's not necessarily a bad thing, I'm just pointing out the difference.
In the mid 1980's or so Tucker modified the carriers in that they changed the way the tracks are supported on either side of the drive sprockets. This machine would have left the factory with a steel framework and plastic "hyfax" on top that the tracks ran along. Later on they removed that framework and went to smaller diameter "damper wheels" to support the track. Those tend to be quieter in operation. The hyfax system works fine, it's just a bit noisier.
If you haven't seen the factory "sedan" style cab I recommend you think about how you intend to use the machine. Basically there are two forward facing seats in front. Then there is a structural bulkhead behind the front seats. The bulkhead is big enough that it basically precludes an adult from crawling from front to back. In the rear there are bench seats that face each other and at the very back of the cab there's a third door. If you really need to carry more than four people, then this is the Tucker cab style for you. Otherwise, I'd suggest you consider a four door.
As far as price, there's a saying that I think is very applicable to used snowcats: "The bitterness of poor quality remains long after the satisfaction of low price".
You will be able to find cheaper Tuckers. However sedans are fairly rare (roughly 3%-5% of Tuckers of this vintage were sedans...and they build 50-100 cats a year). Further, how many of those had front blades? Hint: not many. So the reality is this is a pretty rare machine in what looks to be nice shape. This is just my impression but if this machine represents your needs, you'll be looking for a while to find a similar one.
For some additional reference, here's a link to a really nice four door machine with blade. Check out the photos and you can see the blades framework. I believe this ended up on ebay and sold for somewhere around $20K:
http://www.resortboneyard.com/i/1984-tucker-snocat-1544/1937
Here's a link to a youtube video of another 1544 with a blade: This also ended up on ebay and IIRC went for the mid-teens or so:
[ame="http://www.youtube.com/watch?v=RE3BOuYHh9I"]Tucker on the ice - YouTube[/ame]
