There were edo ram, fp-something before that.
That was on simms. Both long (72 pin) and short (30pins). You had to had two modules for a bank. The biggest module i have is 32mb (64mb per bank)
Then comes the dimms:
edo dimm, pc66, pc100, pc133.
30pin simm were used up to 386, maybe 486, The longer were used up to pentium mmx (~1997-8).
Some later pentium boards had both simm and dimm (pc66) slots.
pc100 was for pII, pIII, K6, K6-2,3. pc133 were just faster pc100 and could be used with early athlons and later pIII.
I remember getting my athlon 700 slotA in 2000 with 128mb pc133.
Then came the DDR technology, which is doubling the transfer at the same speed. So pc133 became pc266. pc400 alias pc3200 runs at 200mhz.
Lets not forget rdram rimms - the high clocked, low width "serial" memory.
The PC800 rimm run at 400mhz but was only 16bits wide compared to 64bit dimms. This gave half the bandwidth of pc400ddr. And thay were expensive,
DDR2 is another modification, making it pissible to transfer data four times the speed of the clock. So DDR2 800 runs at the same clock as DDR 400. The technology made it nessesary to include higher latencies so in order to really benefit of it you need higher clocks.
I really dont know what the memories used to cost. On second hand market in sweden a 256mb stick of pc100 or 133 cost now around 180sek (18-20eur or 24-26usd).
I'm researching for graduate course on Telecommunications. I must present report on cost per years 1990-2007 of RAM. eg. 16MB; 32MB; 128MB;256MB; ...
Prices at retail often vary by 100% or even more between vendors, thus you need to compare apples with apples. First, put some effort into figuring out *which* prices are comparable from year to year. One thing you might look into are "spot" market memory chip prices. Another might be newspaper or magazine ads (or even bulk-mail catalogs) for the same store over the years. I suspect it will be difficult to find vendors that have been in business over the entire time frame; one that has been around a long time is PC Connection, another is Dell.