I hadn't really noticed these so my answer is triggered by your question and, of course, I'm no expert - this is just my instant response, ramble & opinion
![🙃 🙃](https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f643.png)
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Take these first three 18K pieces on the website (attached images). There are others, I just picked these as examples. There is a wide range of saturation and each piece has a different clarity rating, (the second one, for example, is deeply saturated but included). Assuming that pink is your colour (I can take it or leave it, although I'm a sucker for a precision or fancy cut Rose de France amethyst!) I think the first ring is actually quite elegant. The stone is a good size, even saturation and SI clarity. The pendant is neither here nor there.
Spinel is far more durable than, say, a kunzite and the colour won't fade as quickly in sunlight. But it's not as rare as Gemporia presentations want you to believe. Here's a range of stones, different locations, sizes (dimensions, not weight) and colours:
https://www.1stdibs.com/buy/tajikistan-spinel/
The Gemporia stone weights (not dimensions) are quite small compared to some of these examples on 1stDibs, especially for the price (take off the gold & diamond cost). Gemporia also likes to put a premium on a distinct location but I can't see that there's anything different to this location to Myanmar or Ceylon. See image 4 - larger stone, arguably more interesting colour - and I come back to it - colour is only one but a key factor to a value of a gemstone.
To your real question about worth and cost, I think it's possible that these are standard or high prices - I assume that you've seen what the live auction price is normally - about 10-20% lower than the web price? Even then, I don't think they're particularly competitively priced. If you do a search for 18K spinel rings, a few non-Gemporia ones come up but they seem to be either silly money (Pragnells) or about the same. I've noticed that Gemporia adds a hefty premium based on a fraction of gold weight difference between designs and how many of their melee size SI diamonds that they squeeze into the design. The silver and 9K ones are the usual Gemporia fare - included, pale, wishy-washy cluster designs of small stones, probably badly cut and comparatively over-priced. I'm not being snooty about these because "I only do 18K jewellery" - looking at their website, the difference in quality of stone set in cheaper metals is quite stark. Gemporia likes to claim that the quality is no different in silver or the ranges of gold. Either that's sadly true or it's BS and, looking at the Tajik examples in silver/9K I feel it's BS.
That's enough rambling but hope it helps.