Is it possible to use an array as MATCH criteria?

I'm trying to find the lowest price for any product in a group of substitutable products. My thought was to use an array formula but it doesn't seem to work.

	A	B	C	D	E
1	Item	Site1	Site2		Valid
2	one		1.5		one
3	two	2			two
4	three		1		four
5	four	7	8		
6	five	1			
7					
8	Best	0	1.5

The formula in B8 is:

{=MIN(INDEX(B2:B6,MATCH($E$2:$E$4,$A$2:$A$6,0)))}

It's working for Site 2, but only because the MATCH part of the formula only picks up the first item from the list of valid items, rather than the whole array as I had expected.

Is there another way to approach this?