I have an old Strat copy that i would like to get some new pickups for so it sounds better and i will have another decent playing guitar. I play anything from Bloc Party to Underoath. What would be some decent pickups for a strat that are under $150?
Nothing for that price. The problem you are facing is that block party uses a tele and you will need a bridge pickup that is very overwound in order to get that kind of tone. Underoath sound to me like they are using noisless singles but I could be wrong. So my guess is that you could get really really good underoath tone with the right amp and a set of fender Hot noisless single coils.

My suggestion to you would be raise your budget by about $25 to $50 and find yourself a good set of pickups that can do both. I'd suggest a bridge pickup that uses 43awg wire, is wound to around 10K, has forbon bobbins, and anlico 5 magnets. This will give you a tone that sound like something half way between a tele and a P90. It'll be twangy, bright, and slightly nasal. My swingin" hot meets these specs, Bare Knuckles has something in this relm, and so does stephen's designes. I'm not sure if Semoure duncan and DiMarzio sell anything like this that isn't a rail pickup. Just check specs and see what you can dig up on their website.

In the middle I'd go with a hot but not super hot pickup. Something around 7.5 to 8K with 43awg wire, alnico magnets and forbon bobbins. Again this is something that most of your boutique winders will make for you. I could work something (a custom overwound swingin' warm) up for you if you are interested. I'm also sure that Dimarzio and Seymour duncan both have something like this. It will be listed in their medium output range. Just make sure the specs match. I doubt Seymour or DiMarzio will tell you the wire size, but it's a good bet that they will be using 43awg for strat pickups in this output range.

For the neck pickup I'd go with something a little lower output and more traditional. Something that uses 42awg wire and it wound to about 6.2K will give you a slightly hotter than normal strat tone in the neck which will be good for nearly anything that a strat is good for. My swingin cool would fit the bill for this pickup but again, Seymour Duncan and Dimarzio will also have fine pickups to choose from.

This pickup combo will give you pletty of power so you can really drive your amp and it'll give you the modern hot strat tones from the neck and middle while you get a tele like tone from the bridge.
Not taking any online orders.
^ebay could be a great place, but you still have to know what you are looking for. Buying random pickups untill you find something you like could cost you thousands.
Not taking any online orders.