As far as I know it is a genuine chip, but it is a Free Play (no cash value) $1 chip. There are 2 different colors of this chip, both same value. The spelling is just a variant that the manufacturer placed on the chip. Note that there is a $5 arodie chip that spells "Thunder Bird" in 2 words also. The relative value on this chip is influenced by a mix of positive and negative collectibility factors, IMO:
+ It's a chip from the Thunderbird, one of the nice older LV strip properties to collect
+ It's a $1 chip -- lots of $1 collectors out there
+ It's a C&J mold... and in good shape
- It's a Free Play special use chip, not a regular $1 chip
- Not as many collectors of non cash value chips, in general
- Supply of chips unknown. Destruction policies of Free Play / NCV chips may be looser than cash-value chips of a similar age.

I don't think it's counterfeit. C&J mold chips didn't have a problem of counterfeiting as far as I know.

BTW, the chip in question is at:
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1123282332