I expect Marina would ask 40-50m because Tammy is a HG, only 23, proven more than capable to score at least 10+goals in PL, and still has 2 year left in his contract. He also probably have more suitors than other deadwood like Michy, Emerson, Bakayoko, Zappacosta, and Barkley. Let's be real there even if Tammy is quite limited he could still at least scoring goals and get into several clubs like:
Arsenal (Lacazette and Aubameyang has been in decline the last 2 year, Nketiah isn't good enough.)
Wolves (Jose and Silva aren't good enough and there is no guarantee Jimenez can regain his former form)
Spurs (if they sell Kane)
Everton (if they sell DCL)
Villa (He could start there although Watkins is decent)
West Ham (definitely need a new striker)
Southampton (if they sell Ings)
Then there are other clubs outside PL who need striker like Dortmund (if they sell Haaland), Leipzig, Leverkusen, Milan, Roma, and Juventus.