I think there are two issues here.
1) Funding
Fans putting in sponsor money helps fund the stadium. This can be buying a brick that I'm sure will have some name etched in it or something to identify it at a minimal cost. Say £5 for the etching, then £100 for the brick itself (I think £100 sounds expensive for a single brick, but it is also an opportunity to have your name etched in the stadium, so perhaps more could be charged...)
2) Sentiment.
The mosaic idea and similar things tend to be about celebrating the club, the history, the fight for the stadium, the fans and so on, and seem to possibly make (albeit minor) complications to the plans/funding (the mosaic thread linked to didn't indicate the fans would pay)
1) Funding
Fans putting in sponsor money helps fund the stadium. This can be buying a brick that I'm sure will have some name etched in it or something to identify it at a minimal cost. Say £5 for the etching, then £100 for the brick itself (I think £100 sounds expensive for a single brick, but it is also an opportunity to have your name etched in the stadium, so perhaps more could be charged...)
2) Sentiment.
The mosaic idea and similar things tend to be about celebrating the club, the history, the fight for the stadium, the fans and so on, and seem to possibly make (albeit minor) complications to the plans/funding (the mosaic thread linked to didn't indicate the fans would pay)