JimmyP is your man for Mongoose info, I'm sure he has a scan of the M1 ad and I'm certain I saw it posted recently
i DID HAVE BUT I CAN'T SEEM TO FIND IT.
dam caps
The M1 was the USA Mongoose entry bike with low end parts, much like the uk eqiverlant Grand Prix. The bike came with Steel Pro Class rims, Steel Mongoose bars and chromo Main frame with steel forks.
I would say the bike in the pic is worth £120, go for it