Hi Raymo, So... these premium maks 7" and up are quite rare beasties. My Santel is certainly the only one in Australia, and I'd guess likewise Kunama's 8" TEC. After much hunting Alex located an Intes 715D and we know there is also an Intes 815 somewhere in Australia, last known in Victoria.
But if you want one, the real issue is what's currently available new vs secondhand, and you will have a very long wait now for a secondhand one. As Alex said, with Intes closing production the only maks in current production larger than 6" are:
- Skywatcher 180mm
- Orion UK, and
- Questar 7.
If you want to take a look at what comparable maks cost when new, take a look at:
1. APM - back in 2016, the Intes 715D was 3,990 euros, 814D was 5,500 euros, while a 10" would set you back 10,000 - 12,000 euros depending on exact specs. Largest they had was a 40cm (16").
2. Company Seven website (Questar). A Q7 astro version with the fork mount, pier/tripod and a set of Brandons comes in at $US23,000.
3. Orion Optics UK - 20cm f/20 OMC200 is 6,416 UK pounds.
Compared to these the Skywatcher 180mm mak is an absolute bargain and several recent examples I've seen have all been very good, with the last one I owned being very near perfect.
Others: There were also a few large ones made by TEC and AP, but these are out of production and good luck trying to find one.
As for the Santel... I never dreamt I'd own one of these. I knew of three owners online ... until one day Randy Payne decided to sell his, which had been in an observatory and in mint condition. You can still find the list price at
http://www.stellaroptical.com/santel-mk9.htm. What I paid stays between me and Randy. Santel made only 28 MK91 and I expect the production quantities for Intes, TEC and AP are likewise small - few will pay the new prices (new).
Lastly, there is also Ottiche Zen in Venice who made some maks 8" - 10" over the years, but now only make optic sets - not finished OTA's - and their correctors are not AR coated.
Are they worth it ? That's up to you, and what you use it for. I've seen people spend as much and more on triplet 130mm refractors, which are no match. As for SCT's... what is evident from side-by-side tests is that the optical quality of Alex's 715D and the Santel are far better than comparable SCTs. I have yet to see an SCT - of any size - give better resolution than the Santel.