Least expensive waterproof keychain light?

I want to get some inexpensive keychain lights to keep handy in various places and to give away. I can get "fauxton" squeeze lights for under 40¢ a piece, and they are functionally all I need, however they are not more than "splash resistant" and I want IPX7/8 level waterproofing. When I look for this I find a lot of AAA (and larger) lights for $10 and up, most $20 and up. This is a huge jump in price.

Is there a good option for a waterproof keychain light in the $1-$5 range, preferably running on coin cells? If not I guess I'll get the "fauxtons" and attempt my own waterproofing with some caulk or glue. (I consider them disposables anyway.)

Photon 1 or Inova Led.

Streak said:

Photon 1 or Inova Led.

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I didn't realize the Photon was IPX-7. Thanks! Do you know where I can get them for under $5? The Inova Microlight only says IPX-4 unfortunately, unless there is another one I haven't seen.