The value of your stove is determined much like that of a used car:
age; in working order?; in good condition?; size of stove; BTU output rating; condition of glass in window.
If I am correct, your stove is quite similar to the Franco-Belge stoves. In fact, I think Franco-Belge makes tham and markets them as a lower priced alternative to the F-B series.
Last year I scoured the internet and picked up two separate F-B stoves for about $300.00 each. Both were made in the mid 1980s and needed work to put them in working oder. Between the two of them, I made one working stove. So it cost me about $600.00 for a 20 year old stove.
Up unitil a few weeks ago, a member of this forum had a Surdiac stove for sale in the classified section for about $500. or $600. I don't recall any of the details.
Before you dispose of the Surdiac, might I suggest that you give coal a try? Coal will give you the greatest BTU output for your money and your Surdiac will operate even if your electricity goes out.
Whatever you choose, good luck.