Vlookup for data (yield only numeric values)

[AlGuy]

I am working on a spreadsheet and need to automate data reporting. I update the spreadsheet with data on a daily basis.

Consider the table below:

	A	B
1
2	Wednesday, December 26, 2012	6300
3	Thursday, December 27, 2012	NC
4	Friday, December 28, 2012	NC
5	Monday, December 31, 2012	6200
6	Wednesday, January 02, 2013	NC
7	Thursday, January 03, 2013	6080
8	Friday, January 04, 2013	6090
9	Monday, January 07, 2013	NC

<tbody>
</tbody>

I want to get the last 2 Fridays' value. And in case the value of a Friday is not a numeric value (so the cell contains "NC"), the formula should take the closest value going up. In the example below, the formula should yield:
- for the most recent Friday (January 4 2013): 6090 (A basic vlookup formula should work fine here: In B1, I add the date and use the formula: VLOOKUP($B$1,Cours!$1:$1048576,2,FALSE)).
- for the Friday before the most recent: 6300 (The value for that Friday is NC, but since it's not a number, the formula should look for the most recent numeric value which occurred on December 26, 2012). The previous formula would have return "NC", which is not helpful for my calculations.

Thank you to anyone who can help me with solving this issue.