Making deals with other managers is a huge part of the game, not only to help bolster your own squad, but also to ensure plenty of banter and keep the game thriving. Naturally business is busiest during the off-season and early season, and then settles down as managers feel their teams are ready to take on the rest of Europe!
All transfers need to be confirmed in the confirmation section on the forum (you won't miss it) for transparency across the game.
Please see the below links relating to transfers in PBeMFF:
Use this handy spreadsheet (uses OpenOffice, a free software which is also compatible with Excel) and type your player's stats over the top of the default player to generate a *recommended* value for the player. These are rough guides and the market changes based on what's in demand at any given time (for example defenders with high passing tend to be desirable)