FWIW, I have the following for my Mercury Mk 3:
Connex 8-08 & 3 or 4 KMC Z-1. I bought these online in UK & Germany, cost around USD 15 each, if memory serves.
(Currently, similar chains in Canada are between C$16 and $20, so the reference points above are still valid.)
On my Raven, I used KMC 8x98, which cost a little less, and worked very well. I used to change my chain after ~4000-5000 km.