Lambert would indeed be a smart investment in that price range, regardless of his age. Flawless penalty and superb free kick taker, good in the air, strong, technically up to par for the football Rodgers likes to play, and has a past with the club/city already. I don't see how you could go wrong with that deal, especially if we're looking at him replacing Aspas and/or Borini. A different player in that regard, but a more accomplished one that can offer something lacking from the current options and add some more variety to your attack (as if it doesn't have enough already

).
Lambert, Moreno, Lallana, and Lovren would be an excellent summer. Team still needs another defensive minded midfielder and perhaps a winger though, but those additions would really be key and add some new elements of strength to the squad still lacking.