OK, you've got 50USD and your target is to get someone the best possible range of lights. Ideally you'll include at least a light for their keychain, a small pocket light, a floody light and a thrower.
The budget is for lights only, so no need to include cells or a charger. Let's see what you can come up with and just how much it is possible to get these days for this small sum.
Get a WF-501B for $14.99 At TMart and a C10 at DX $20.30 and come in under budget. Besides I think (hope) the C10 is a better thrower than the C8. I have 3 on order.
$20 Ultrafire C8 (Ebay), these can be found with either XRE, XML or XPG... pick whichever you want. XRE for throw, XML for floody throw, XPG for something in-between.
Id buy one Fenix E21, I think they are close to 35$.
Then one coin cell fake photon (those are very handy), cost about 1$ at the dollar store. And they last a loooooooong time. Maybe Id buy the person QTY=2 of these.
Then a Fenix E01 AAA light, those are really handy, about 15$.