# the magical plus of weapons follow the exact same pricing formula as in 3E, except that +3 weapons are priced as if they were +4 items. That is, the price is the bonus squared times a thousand. This is simply not valid anylonger in 5E, since there is only one level of damage resistance. ALL magic weapons bypass resistance, and so ALL magic weapons need a hefty surcharge. The difference between a +2 sword and a +3 sword might have been significant once (remember 3E featured different schemes for damage resistance in 3.0 and 3.5) but is no longer so. Just "plus one" to your hit is of course nice, but hardly vital, especially in the face of 5E's much lower monster AC over the board. And "plus one" damage is almost inconsequential.
# So a real 5E take of magic weapons might want to set a base price of 10000 gp for ANY weapon that registers as magical (that is, bypasses magic resistance). THEN you can have +1000, +4000 and +9000 for +1, +2 and +3 enchantments, respectively.
In the end, such a scheme would indicate that a +3 weapon is roughly twice as desirable as a +1 weapon, and not sixteen times as Sane would have you believe! But more importantly, that no magic weapon is less desirable than ordinary full plate, or even close to it.