Mail order will probably incur more shipping charges than the value of the parts
Yes they are only £0.91 here:-
http://uk.farnell.com/texas-instruments/cd74hc4067e/logic-mux-demux-analog-hs-24dip/dp/1740160
The trick is to order other stuff to get you up to the free shipping total, which is about £25 or so here. Once you get into electronics you will find there is always stuff you want or need. Why they even sell Arduiunos and Raspberry Pis and lots of other stuff. It is a good excuse to get interesting things. You can justify it by saying to yourself, "well I had to get it to get me up to the free postage value so in effect it is free". 