With regards to the cost of installation, it is my understanding that with the type of "seats" being talked about that you actually get more standing capacity than sitting capacity. For a section of 40 seats when in the sitting configuration, (as would be needed for UEFA competitions ), you would be able to have maybe 72 standing spaces. Figures taken from http://www.safestandingroadshow.co.uk/the-case-for-safe-standing/case-for-3
With that in mind if there was to be an extra set-up fee for the first season ticket in that area then it may not need to be the full cost of the installation. Alternatively there could be 2 ticket options, pay £100 extra on the first season, and possibly a bit more subsequently, and you get the seat when in that configuration, or have no set-up cost, possibly cheaper ticket, but you don't get a spot for all seated games.
Of course you would have to take walk ups who want to stand into the figures, but it might give more leeway on the costs.