Table 1 (Purchases):
Column A has a list of part numbers.
Column B has a list of purchase dates.
Column C has a list of material costs unique to the part number and
part ID.

Table 2 (Sales):
Column A has part numbers
Column B has sale dates
Column C - needs to have the purchase cost from the most recent
purchase of this part

I'd like to look up the ID in table 1 column A, then find the purchase
date closest to but before my sale date, and return the purchase cost
from table 1 column C to table 2 column C.

I know how to do array-entered sum(if..) statements, but I only know
how to get exact matches, not closest matches.

And I know how to do index(match...), but I can't figure out how to do
two matches inside one index function.

Thanks.