What grinder are they offering? a BCG800 or a BCG450. If the former, that sweetens the deal - if the latter, dont bother.
Do you already have a grinder? Are you looking for a new one?
Whats your budget? looks like its between $380 and $500. Have you checked the for sale section? There are second hand silvias in excellent condition coming up in there often for around that price range. I would highly recommend. Not only will a 2nd hand silvia produce better coffee, it will last longer and be worth more money when youre done with it.
A VV, BES840 or 2nd hand Silvia will cost you (say) about $400 now. If theyre still working in 3 years time, the VV will be worth about $100, the BES840, id guess about $50. The Silvia will still be working and probably worth between $200-$300 (depending on how good condition you keep it).
Net result - VV costs you $300, BES840 $350, Silvia $100-$200.
My second crack. (2 cents - not second crack ;D )