The closest thing to an errata to this would be the loot rules used by the most recent version of Lair Assault.
We use straightforward rules to equip characters for their deadly battles. Each character receives one magic item of one level higher than their level (level + 1), one of their level (level + 0), and one of one level lower than their level (level – 1). In addition, characters receive gold pieces equal to the value of one magic item of one level lower than their level (level – 1) to buy other equipment they think they’ll need. Each character may have no more than two consumable items (like potions or magic ammunition) equal to or less than the challenge’s level, and no more than one rare magic item. Note that players may equip their characters with magic items that are less than the stated levels if they so choose.
https://www.wizards.com/dnd/Event.aspx?x=dnd/4new/event/dndlairassault (note that link will probably be invalid shortly after Lair Assault ends on May 31st, 2013)
Note that you can acquire as many common and uncommon items as you desire, the only rarity restriction is one rare magic item. Common and Uncommon are meaningless distinctions in this process.
The original buy-in rules were designed before Rarity was introduced.
The confusion about common, uncommon, and rare items was introduced much later, with Essentials. Although Wizards back-introduced rarity to items, it is very inconsistent across its many books, with some "uncommon" items seeming more powerful than their "rare" counterparts. I find rarity to be a poor indicator of actual value and don't use the system myself.
The buy-in rules were designed for a single higher level character entering an existing campaign. If you are building an entire party at higher levels, you can instead pool all the treasure parcels they ought to have received.
Although it is considerably more time-consuming, an alternative to the +-1 three-item buy-in rules is the full parcel buy-in rules. Basically, add up all the parcels for the levels below the new characters' level. So if you're starting a Paragon campaign at level 11, pool together the parcels for levels 1 through 10.
In this example, you'd hand out 40,795g to the whole party (versus 25,000 for a party of 5) and you'd hand out items of the following levels:
- Level 2: 1
- Level 3: 2
- Level 4: 3
- Level 5: 4
- Level 6: 4
- Level 7: 4
- Level 8: 4
- Level 9: 4
- Level 10: 4
- Level 11: 4
- Level 12: 3
- Level 13: 2
- Level 14: 1
(as opposed to 5 level 10s, 5 level 11s, 5 level 12s. Note that the loss of three +2 items from 11 and 12 are replaced by 3 +2 items from 13 and 14).
This system requires the players to work together when assigning their items from a common pool, but more accurately reflects what a team of players are expected to have acquired during their campaign. Note, however, that this does not account for items players ought to have lost during their campaign, consumables consumed, money spent on services, etc. As a result, you may wish to reduce or even eliminate the monetary treasure from the pool system.