Heres my list:
The GG: Regularly resells for $350 in the ecf classifieds. $350 for a tube mod with a 901 connection. It was a beautiful design when it came out and I still think its one of the most beautiful mods on the market. China still hasn't gotten the cloning right. But the GG is a great, ORIGINAL mod, and the mod maker is a good man. He doesn't like all the cloning going on but I think he invented a very versitile design. So personally, I like to see the GG clones on the market. Especially since I will NEVER have $350 for a real GG.
The Provari: At $160 for the basic mod without batteries or charger or atty or juice. $175 for one with color. Add on another $15 for a blue or green LED. Provape likes to take our money! $30 for a replacement end cap. $25 for the extension tube? I mean c'mon? Your CNC machines have been paid for 10000x over and we're still getting bloody noses at checkout. But the quality is VIRTUALLY UNMATCHED! Are they expensive? Hell yes. Remember the Diamante? It had a red, blue, green, & yellow LED. You could choose which one you wanted to use in the menu system. With the Provari, you get ONE choice and you have to pay for it!

While I think the Provari could have more coupons and more sales, overall, I believe the price is worth the product. At $200 for a battery regulating tube, it better be good.
The Caravela, the ZEN mods, the Poldiac from MMvapers. All extremely expensive for my tastes. I would love to try them but I could never afford to buy them.

The Darwin, in good condition, can sell for upwards of $400+ dollars used these days. (although some people haven't gotten the memo and you sometimes see them for $200! But they do sell for $400+) The Darwin is a classic collectors mod, being the very first variable wattage device that was mass produced for the e-cig enthusiasts.
Theres the Teamon, which is a regular 510 threaded mechanical mod made out of either stainless steel or titanium depending on your taste. The caps are 24k, 14k, or 10k gold plated depending on your budget, and the bottom mounted push button is actually accented with an opal jewel. The teamon is made in france and its got to be one of the most expensive bare-bones mechanical mods on the market today that doesn't come with an genisis atty.
Some ZEN mods sell for as much as $500 new. The Zen mods that are made from Titanium sell for $500 new and can sell for more used! There is also a Titanium Genisis atomizer on the market called the BLISS, it's pretty readily available, and it sells new for $400-500. JUST the ATTY!

& people BUY IT! LMAO!
As already mentioned, the Mark Bugs mods are ridiculously expensive but they have one of the tightest followings in the game! & the OPUS D is one of the more expensive regulated mods on the market tday.