What's the real price?

I could really do with a decent light next to where I sit in the study.  It is just behind bear so I can watch what he is doing on the computer.  Today it was watching Donald Duck cartoons on YouTube.  I have two pairs of curtains I am going to be sewing by hand (not very hard to do) and having a decent light will make it a lot easier, as no natural light falls where I sit at any point of the day.

I don't really want to move the light from the living room, as I find it very useful there when I am keeping DH company and knitting/cross stitch/reading in the living room.  Carting a floor lamp from room to room is doable, and a small thing compared to what some people do, but not top of my list.  I know I am going to spend far too much time over the forty two days of the summer watching bear play computer games/browse ceebeebies website/browse sesame street website/try and educate me about minecraft and I would like to be able to do something useful with my hands as I was stuck there.

I have seen a floor lamp identical to the brilliant one I have in the living room which is perfect.  On the IKEA website it is £11

If I have it delivered then it adds £15 on to the price, so it comes to £26.  If I order it online and then have it delivered there is a further £15, so a total of £41.  I have seen it on ebay at £24.95, inclusive.  

It seems obvious that I should go to IKEA and get the lamp.  However going to IKEA is not straight forward, it requires two buses at least, so a saver ticket at £4.50.  This puts the real minimum price of the lamp at £15.50.  It would be £9.45 more to get it on ebay and I would get nectar points.  The question is, how much do I actually want the lamp?  And would I be strong enough to leave IKEA after only buying the lamp?  I don't actually know anyone who has managed to come away from IKEA with just the one thing they went in for.  Normally I keep the excess spends low, but a coffee, a cake and a pack of tealights would easily add £5, and it is really hard to avoid the kitchen gadget area and I am lusting after some new storage jars, so hard to believe that I would be able to keep any additional spends to under £10.  

I think I will see if I can find any lamps around the house that I can use instead.  However I think it is interesting to see how things like transport and 'spends' can eat away at the benefit of a bargain.