The first generation iPad Air is long ago obsolete - and by now has limited utility or capability, more so as the original version with which the iPad was shipped may still be present. Very few (if any) Apps will be available from the App Store that remain compatible with the iPad and iOS7.
As for how "collectible" it may be, consider that there were likely many millions produced - of which many may still be in use with diehard users. Other than to a specialist collector, it will have little more than curiosity value. Also consider that the iPad's battery is very likely to be approaching its demise.