Where can you buy 'bits'?

Sorry, don't know if this is the right section for this or not -

I am assembling some trueborn and the box set only comes with one blaster. Not ideal when you want four, and I don't have the requisite bits for conversions either. Is there a way to purchase individual parts from GW? I will keep looking on ebay too but buying direct as and when needed would be the best solution for me.

Thanks!

There are plenty facebook groups that are specialized in second-hand miniatures transactions. I buy a lot from there.
One thing you can do is MP a seller that sells DE, and ask : "Do you have unused bits and sprues ?". Often time he didn't even think about selling those, and will sell them for a great price.

There are websites such as Bitzbox and Bitsandkits, but they are almosty always out of stock on most things (I really have no idea why they bother).

There is also the Barterport is this very website.
Some people may have spare Dark Eldar bits they'rew willing to part with!

not suitable for dark city