RAW, when a player wishes to requisition an item, the GM gives him a modifier based on its availability which is in turn, further modified by the quality of the item the player wishes. This strikes me as a bit odd and I was wondering if anyone has tried modifying the roll by availability only (of course, assuming the GM allows the roll in the first place) and then used the different available quality levels to act as a range, so the quality of the item the player receives his dependent on his roll rather than by simply going "Yes/No".

I've worded that really badly, but hopefully you know what I mean. If not, I'll have another go once I've had some sleep...

Yeah, because quality is gradual I think it's good idea, mechanically, to allow players to achieve poor quality equipment if they rolled 1 DoF and Good or even Best if they rolled 2 DoS or 3 DoS. It could ease the pain after failing the test or give a reward for stacking inf bonuses before it.