I've just sold a Trilogo Luke Poncho on Meccano Trilogo for £140. It had similar bubble damage but to one end only and was in better condition card wise and without touch ups.
That said, Stephane and Yann's Collector's Handbook gives Luke Poncho 3/5 in terms of rarity and the AT-ST Driver as 4/5 in terms of rarity on Meccano cards. Which, in theory, makes it as hard to find as a trilogo Jawa
I have some issues with the rarity guide, but then I guess rarity does not automatically translate into desirability.
Given the damage and the touch ups I just can't see if being worth more than about £60 to the right person. I should point out that is my feeling on it's value rather than what I know it to be worth. In the world of Meccano cards, if someone turned round and said it was worth £200 I wouldn't be surprised, just think Meccano collectors were even madder than I already did
I don't know who you could approach to ask for an impartial value. Maybe Stephane Faucourt and Yann Leroux themselves. They're good guys.