Just note, they are considerably cheaper on their own store, amplified by the fact that they do 20 percent discounts for bundle purchases. The price difference is not trivial, several dollars per airfield, i.e Redhill will set you back over £16 on Orbx, but only £12.95 on their own site, plus if you spend over £25 you’ll get a further 20 percent so another £2.59 off, so around £10.50.
I have every single one of their airfields and they are all exceptional quality so you can buy any with confidence.