100 Simpoints = $1 (I don't know how much in pounds ^_^)
One hairstyle is 100 Simpoints so it's a Dollar a hairstyle which isn't that bad but it adds up quickly :P
If you register your Sims 3 game on the Website you'll get a 1000 free simpoints and there should be a code for another 1000 free simpoints in the base game box ^_^
On Expansion/Stuff packs? Yes, sometimes they do 50% off or Buy one get one free, for the 14th anniversary they gave away Town Life stuff for free but if your talking about Simpoints then no, they used to be £7 for 1,000 but they bummed it down a bit.
There will be more to buy for the Sims 4 @[email protected]
Sooo much stuff it's like Black Friday but I'm the one grabbing all the stuff instead of being shoved in the corner :3