I have all the EBRs (lots of FALs, HK91s, ARs, AKs), mil-surps and pistols, normal cap mags and such that I need. I did order...and hopefully will soon receive...a .50 BMG rifle.
Other than that...the best thing to lay in is a LOT of ammo. If the administration is somewhat friendly to gun owners, ammo will still rise in price.
If the administration is NOT friendly to gun owners, I believe that is what they will make difficult to obtain. Banning/taxing/environmental restrictions on ammo are more politically palatable and just as effective way to create restrictions on gun ownership and shooting.
No ammo = no usefulness of guns.