Dean,
I went down that path several months ago.
If you do a search for vinyl cutters, you will come up with "thousands". There a lots of cheap copies, and as I found out copies of copies.

There are lots on ebay.

Regarding the "chinese copies", they seem to work, but are often noisy, and not always well supported from a software wise.

Stay away from 12 inch models, I had a small one for years, and it was always too small.

Finally I went for a Roland GX-24. This was quite a lot more than my original budget, but it is a beautiful machine. 24 inch wide, cuts down to really small lettering (something the cheaper units struggle with).

The thing is, once you have one, you will start to use it for more and more, and as I have found out, I now have a growing business in my aeromodelling club.

I have only just started cutting paint masks, they worked fantastically well.

BUT
Cutting monokote? well I haven't been successful yet. It doesn't feed through the cutter, because normal vinyl is attached to the carrier, which the cutter relies on. With monokote, as soon as you cut, it lifts away and jams the cutter. I have tried on a different cutter, same result.

I hope there is a way to cut monokote, as it would certainly grow my options even more.

With the cutter.
I use Illustrator to design, as you need vectors.
Then I use a third party software called Signcut, found at www.sc-x2.com which does a great job of controlling the cutter (much better than the supplied software).

Then, the sky is the limit.
But be warned, like everything, there is a learning curve in dealing with vinyl, multilayer decals etc.
But it's great for your 'planes.

My 2c worth,
Bruce