Entering tabular data into a ticket

Is there existing support, a plugin, a recipe, or even any hints for
entering tabular data in a ticket?

The particular application is something like a purchase request.
There are standard fields that apply to the ticket as a whole –
requester, date opened, due date, etc. – but core data for the ticket
would logically be stored in a table. In the purchase request case,
some columns might be part description and quantity, and the user
would enter one row for each item type that they need. We would much
prefer to track the set of items together rather than splitting each
row into a separate ticket.

(Bonus points if columns can be defined in terms of custom fields, to
inherit things like their hyperlink target policies. I did not see
discussion of this kind of feature in the plugin, extension or wish
lists on the wiki, and the closest I found in the mailing list
archives was an August 2008 post asking something rather different.)

Michael Poole