It's hard to tell without knowing the make of each gun. I'd guess you could get £100 for each but they could be worth more. If the brand is unknown you'll need to assume it's the cheapest.
You need to Google images of "m14 socom airsoft" and see if you can work out what you have. Maybe cyma, g&g, TM, snow wolf or jg (if they made a socom variant), aps is another maybe. Could be others depending on how old it us.
For the m4 just find one with the same receiver markings.
