I'm with mr. *****ens on this one. roomie is taking advantage and I think if you pay - even just this once - it sets the tone for the rest of your stay with this roommates.
It may have been different if you were there at the time of purchase to give input or agree to the terms but really?? no. tell her no.

I have quite some experience of living with flatmates, and I see the other side of this. There is clearly a need for a table, even in the op it's mentioned.

Said flatmate went out of her way to buy the table, arrange or maybe even do the delivery and/or construction herself and save amity the hassle of doing any of that.

Amity will no doubt use the table a whole lot during the year, eat on it, have parties around it, probably even have sex on it. I think the whole deal is worth around twenty pounds, and she doesn't even have to pay straight away.

I think *****ens and Mae are giving some bad advice here. JMHO.

Plus, your flatmates will think you are being a tight arsed difficult ***** if you cause a stink about it, and, in my humble opinion, justifiably so

I think you're in the right, she could have easily consulted you about the table first. I would point that out to her next time she asks you for the money. On the other hand if it's going to cause a major stress I'd probably just give her the money but still point out that you'd like to be consulted before any more purchases are made on your behalf.

I would pay up for the sake of civility since we all know these houseshares can go horribly wrong from much smaller bull**** than this.

BUT while paying up I would also make it extremely clear that I'm annoyed about not being consulted about it beforehand and in future I will not be paying for any such things unless I have brought into that decision making process.

I don't do table sex. ESPECIALLY not in shared houses.

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