WatchGecko currently have 20% off all their eBay watch straps using the above code until 23/6. It auto-applied for me, but ymmv.
Many items are only marked down from full price, so possibly better to wait for other deals if there's something specific you're after.
Personally I look for anything under a tenner to be decent value, so this nylon strap at £4.80 delivered fits the bill.
A black version
is also available for 80p more.
I bought a similar strap from WG last year and am very pleased with the wear and comfort of it. Think it suits my Forrester nicely