Like Beano Comic Library, this is a collectible title though finding true near mint copies can prove challenging as they tend to be well read. Turning the cover back too far can result in spine creases.
These comics show up for sale pretty regularly on eBay UK though early issues less often.
There are no specifically rare issues to my knowledge though early ones in very high grade are hard to come by and the last few issues will be less common owing to reduced print runs.
I have been informed that very late issues of this title were fetching up to £30 on eBay UK recently. Didn't see it myself (working full time) but I will monitor this situation for some future sales to confirm this situation.
Stop Press! following an auction on eBay UK May 2013, some issues in the #280s currently at £31 each! And sure enough, they (numbers 265, 274 and 285) went for that £31 each. Someone put in a killer bid and no-one challenged it. I will keep and eye out for late number Dandy and Beano comic libraries and see if similar prices are achieved.
Note: some PR issues may have no value. Selected issues in FN, VF or VF/NM may not exist in some titles.