Ebay Seller being Greedy !!, actually that is a reasonable price, Opening price is £ 5.99, out of that is £1.40 postage, 60p Ebay fees and 40p Paypal fees, then packaging cost and the trip to the post office, not including the latter 2 they will make £3.59 profit. If they bought the mag then they are not making anything just recouping some of their costs.
If you buy it from the site which now sells the back issues it will cost £5.40 + Postage £1.99 ( Bearing in mind postage is only £ 1.40 for that magazine assuming posting 2nd class (1st is £ 1.69) , so £ 7.39 .
I forget the price but the May issue before lock down was going for a bit more than that by one seller in Scotland.