I'm a bit bummed about the magic item chart and rules on page 129 of the DMG.
As a rough rule of thumb (YMMV), a GP is worth about $100.
So the chart becomes:
Common: $10,000 and 4 days to craft, minimum 3rd level
Uncommon: $50,000 and 20 days to craft, minimum 3rd level
Rare: $500,000 and 7 months to craft, minimum 6th level
Very Rare: $5,000,000 and 5.5 years to craft, minimum 11th level
Legendary: $50,000,000 and 55 years to craft, minimum 17th level
These times assume that the crafter is not stopping. If he takes breaks, it takes longer. And yes, I realize that multiple crafters can work together, but that is white noise. If any of them quit (die, whatever), the item can no longer be made (theoretically) and even 5 crafters are not going to want to spend 11 years each making a legendary item.
This has no bearing on the game whatsoever. The game is about the PCs. If the PCs cannot craft items, this is somewhat unnecessary information for the DM. If the PCs can craft items, then the cost are so high and timeframes so long that they will almost never be used in an actual game.
I actually like the original playtest values:
Common, 2+, 50–100 gp
Uncommon, 3+, 100–500 gp
Rare, 5+, 500–2,000 gp
Very rare, 7+, 2,000–5,000 gp
Legendary, 9+, 5,000–10,000 gp
that @
CapnZapp listed. Even with the same 25 GP per day, this works out to:
Common: $5000 to $10,000 and 2 to 4 days to craft
Uncommon: $10,000 to $50,000 and 4 to 20 days to craft
Rare: $50,000 to $200,000 and 20 to 80 days to craft
Very Rare: $200,000 to $500,000 and 80 to 200 days to craft
Legendary: $500,000 to $1,000,000 and 200 to 400 days to craft
Now, someone might say that if legendary items only take a year to craft, there would be a bunch of them. Well, yes and no. They still require at least a half million dollars (i.e. 5,000 GP) to create and they still require (with the revised level minimum) 17th level PCs/NPCs (who often have better things to do) to do so.
Also, there is the problem of consumable items which the DMG does not really discuss. An Arrow of Slaying in the current model costs 50,000 GP ($5,000,000 ) and 5.5 years to craft. Theoretically. Same for a +3 arrow (or maybe you can create 20 of them for that cost/time, but the rules are unclear).
The cost / time for consumable items should be much lower, but the PHB already establishes a Potion of Healing at 50 GP (which if you think about it, $5000 is REALLY prohibitively expensive).
The rules here are just very weak, almost unusable, and beg to be houseruled.
A simple houserule is to make the lower cost the one for the consumables (and change the equation for it) and make the higher cost the one for most items. A group of consumables (like 20 +3 arrows) would cost the higher cost and time:
Common, 3+, 50 (2 days), 100 gp (4 days)
Uncommon, 3+, 150 (6 days), 500 gp (20 days)
Rare, 6+, 350 (2 weeks), 2,000 gp (80 days)
Very rare, 11+, 750 (1 month), 5,000 gp (~7 months)
Legendary, 17+, 1500 (2 months), 10,000 gp (~14 months)