Just over combo pack if you're looking at per-unit costs. You most likely don't actually need domes for every tray since you only really need them for the first couple months after sowing seeds, so you can get twice as many trays, that are each ~1/3 longer with larger, deeper cells for ~60% more.
Alternatively, breaking it down in terms of roughly 10-tray units and including shipping costs:
Amazon: $52/10 trays but with shorter, smaller cells and each tray is ~25% smaller than a standard 1020
GM combo pack: $72/9 full-size trays with shorter cells
GM individuals: $42/10 full-size trays with deep cells, but only 5 domes to rotate as needed.
Again, all that said this only matters if you have space for or plan to eventually use that many trays since GM only sells the individual trays/flats in 10-packs minimum. If you only need or have room for a few smaller trays then there's nothing especially wrong with the Amazon thing you linked other than just having shorter, smaller cells, but I have a couple trays of drosera in similar cells that have done fine - they just eventually grow roots out the bottom and can overlap into neighboring cells if they're big enough around. Here's a picture from a few months ago of 1-year-old unfed Tamlins and Emerald's Envy growing in 1.9"x1.9"x2.375" cells vs the Amazon tray's 1.5"x 1.5"x 2" if it helps:
Cable Routing.jpg (874.16 KiB) Viewed 1614 times
Of course they've grown a decent bit since then, but this should give you an idea anyway. For comparison, the deep inserts from GM measure (2" x 2.25" x 3.25", 36-cell) or (1.56" x 2.36" x 3.13", 48-cell).
Another consideration, these plants don't usually need a lot of horizontal space for single plants (e.g. propping cuttings or pullings) since they normally just grow a few roots basically straight down BUT larger cells can allow more plants per cell (e.g. sowing seeds - multiple seeds needed per cell so you don't end up with a lot of empty cells).
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