For entertainment sake, I thought I'd post some observations on the last 3 years of watching the SW market on eBay.  Take whatever is here with a grain of salt.  I don't account for print varations in my data, and I dont track every SW module - I usually skip modules that are in bad condition, even for being SW.  I lump shipping cost in with the price I record (since it's data for me only, the shipping should remain relative).  I also only skimmed my data, leaving out things that wouldnt come across well (for example, I'd probably put RPGA1-4 in best price stability - but they are high end, and in my head, in a different category).

Most commonly sold SW modules - C2, M1, M2, S3, X8
Least commonly seen SW modules (OK, I lie.  I dropped some since I still want them for my collection.  No point in increasing competition) - C6, DDA3, I10
Most overpaid for modules based on availability (above what I would call "baseline" price for most common SW modules) - CM8, DA3, T1, U1, WGA4

Awards for best price bloat in shortest amount of time (fastest increase in price (at least 33% increase) over shortest time) - A2, N1, M5, X13
Awards for best price stability (least amount of variance between sales) - B7, CM2, UK2, WG12, WGA2
Awards for best consistent fluxuation (price is always all over the place) - A1, A2, A3, A4, CM4, D3, I9, S3

From the last 6 months or so, I'd speculate that at least a few new "heavys" have waded into the SW fray.  Or they are so oldschool that they were not active 3 to 4 years ago when I started.  There are also a bunch of new collectors it would appear who fall into the midrange who have a taste for SW.  I also observe that alot of regular resellers have boosted thier prices to match new demand.  In some cases, laughably so, until someone actually buys the item I am laughing at, then I scratch my head.
"Runs" of modules always generate more interest and result in higher end prices.  Listing RPGA1-4 at the same time usually pulls more $ as bidders try to win all 4.
A1-4 seem to be fan favorites, usually drawing lots of bids, and sometimes running away.