Nope, you're not crazy.
Pricing is a weird topic. There is no true regulation in the paintball market, so you will see wide swings in prices and just timing issues.
For example, yes, you can find an automag for $50 and what not. On eBay it may be around $100.
The best way to figure out pricing is to search the old threads and what they are listed for. The bluebook is nice to have, but it isn't up to date and it is mostly generalities. Context and condition are factors to consider when looking at prices.
For example, take a automag/minimag classic. Classic valve, single trigger frame, and in ok condition maybe sells for $50.
Compare to say an automag/minimag. It has a retro valve or a classic valve with level 10 bolt. Double trigger, etc,etc.
Well the price would be higher than your base mag.
Lastly, some people list things at really high prices.
"I bought my automag blah blah blah back in the day for $1000, I'm listing it on ebay for $800 after 12 years...."
Basically in my mind here's the pricing scheme.
Classic Mag, no frills $55-100
RT Mags $150-200
PneuMags with say an X-Valve -$300ish
Emags - $350ish and up
Xmags - $600+
Really custom mags, CNC, Euros, etc. $?