The general thing people miss is that whether or not something costs £ X new, it does not equate to £ X used this includes 'upgrade' parts. The accepted rule of thumb on this forum is generally 2/3s original price. Hence, my PPS K98K which I have been contemplating selling cost me £450 new. I have 5 mags at £50 each. I wouldnt dream of asking full RRP despite it being skirmished only twice.