whoa nelly, it's been a long time since I've made a price suggestion. Let's hope I'm not too rusty.

Noticed this had no price. Lets look at the market.

Every seller I could find:

http://www.tf2outpost.com/trade/23379240 1 key

http://www.tf2outpost.com/trade/22738642 1 key month old

http://www.tf2outpost.com/trade/22553341 1 key month old

http://www.tf2outpost.com/trade/22738613 2 keys but it's level 100 markup

http://backpack.tf/profiles/76561198024867201 this guy has a classified for a key (rest of the classifieds are the same as the linked outpost listings)

http://bazaar.tf/trade/1052522 1 key 3 weeks old

http://bazaar.tf/trade/1066809 no price, no offers week old

http://bazaar.tf/trade/1077528 no price, no offers, looks like he's looking for a key

http://bazaar.tf/trade/924842 no price, was offered some amount a month ago but unsold as far as I can tell.

http://bazaar.tf/trade/1049934 1 key, 3 weeks old. No longer has in inventory so assumed sold.

http://bazaar.tf/trade/415002 no price. last activity on the trade was 8 months ago. only included for completeness

http://www.tf2outpost.com/trade/23373371 1 key + 3 ref for a spelled one, over a key no matter how you value the spell, unsold

Buyers:

Ignored those who were probably looking for the haunted version even though they listed clean, or were extreme lowballing. Most of the rest were general craft hat lowballers, and I ignored those as well after making sure there was no evidence of a sale in the comments (over a dozen of those).

http://www.tf2outpost.com/trade/23129318 looking for white and not giving a price, not likely to be useful unless the off chance he gets one

http://bazaar.tf/trade/1009810 looking to discuss, has not been offered in a month

http://bazaar.tf/trade/558586 no specific price, no offer in 10 months

none being sold by tf2wh

trade.tf lists price at 2.22 but says itself that price is "extremely uncertain". With no bp price and a rare item, I think it's natural there are occasional low trades.

So that's all the evidence I can find, but I think it's the best that can be done unless someone can point out actual sales. 1 key is in line with other rare clean halloween items that have a cheaper haunted variant.

http://bazaar.tf/trade/1077528 followed up on this one, since I noticed previous owner was someone selling another carious chameleon, but turns out the current owner transmoged it from a grease monkey