The formula to calculate the wastage factor for any level of material efficiency is:

WF = BWF / ( ME + 1 )

WF = wastage factor after ME research
ME = new material efficiency of the BPO
BWF = base wastage factor for the BPO (example: 0.1 for ammo)

And now for the more important steps in ME precalculated (for 0.1 BWF):

Most people, who know the above formula won't pay extra for a BPO/BPC if it's over ME20, since the benefits aren't usually that noticable and the time required to research even a small benefit is usually not worth it on BPOs that have long research times.

Of course sticking some ammo BPO in for ME100 research won't hurt anyone, since they are researched quite fast, but on ship BPOs you might wanna reconsider how much time you have to sacrifice for how much benefit.

Have fun with your BPOs :)

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