Keep in mind, if you have the FP kit, you may have a roller ball pen in the same kit. If you do, you can do one of two things, you can "try one out" JUst buy a spare nib from CSUSA and some refills. then you can swap that nib end into the pen that was a RB. (BTW, it's a great upsale to have the extra FP ends for some kits. For those who want the FP but don't know if they will like it, being able to convert back to a RB can break a sale. The other thing would be to take the nib holder from the kit you have and use that one. I would recomend buying a spare. The new nib will come with the screw in barrel. So if you buy one of their nib's and a converter you can make any one of them a FP.
As for bottled ink, I think the best deal to test some ink is from The Pear Tree, Co.
www.peartreepens.com There you can request up to 4 samples that will ship in small screw cap glass bottles and hold enough to fill a pen once (a full bottle may fill 6 times, but the bottle is not full) He will ship you 4 colors from a vast aray of ink for $2.95 Shipped!! There are 2 very good things from out stand point. First, we can order a few colors to try out for us or our customers. B) Those little bottles are the best thing to have for sale. If you have s full bottle of ink in the standard black/blue you can transfer some from your large bottle into these small vials and include them as a "starter ink" for the piston pump. Keep it simple, blue & black and maybe have a small list of places to buy bottled ink. There was a lot of intrest in FP's but many did not know how well they behave and how wide the range of inks are now. I personaly have the Private Reserve "Burgandy Mist" in my daily user and love the deep maroon color.
Here is the vial to compare against a bottle of ink.