£300-£500 is an awkward price range for binos, not quite enough for 2nd hand Swarovskis but, in my opinion, too much to spend on lesser makes. There is no doubt that some of the mid range binos are very very good these days but the problem is you don't get the back up of the top brands and the resale value is very low.
I am lucky in that I have accumulated a couple of spare pairs of good binos over the years so I am not too precious about leaving those in the truck, if they get stolen NFU can take the hit, but I also have an old pair of Opticron 8x40 rubber armoured poro prisms that live in my work van and get lent to people, they are surprisingly good and very light. A couple of times I have used them for stalking if i've forgotten my better ones or its been an improptu outing and ive been very happy with them. Most birding shops like Cley-spy always have a few ex-trade ins like this in stock for about £50.