I was watching both of those Bank-A-Ball's and agree that the non-worker is strong money but the other one isn't too fair off IMHO, if you could get it for a grand I think you'd be good. Outside of the iconic games there are plenty of EM's that are worth north of £1k, take that Hit The Desk on eBay for example, but it's a limited market you're selling into.
I paid £1200 for my Jet Spin a few years ago and was pretty happy with that price and I won the auction for the Pyramid yesterday at £770 which I think is a bargain for such a relatively rare Gottlieb!
To me, Gottlieb EM's are mostly worth more than Bally and Williams ones, with the usual exceptions with wedgeheads commanding some of the highest prices.
If anyone has a Bally Star-Jet they want to sell me for under £1K then give me a shout