Bat'leth je' vIneH
I want to buy a Bat'leth for my Lingots. Qapla'
We have no influence on which items are offered for sale in the lingot store for lingots or gems, I'm afraid :)
Also, I think you want to say betleH vIje' vIneH -- the Klingon word for a bat'leth is betleH. (And if you leave off the vI- from vIje', it changes the meaning from "I want that I buy" to "I want that he/she buys", i.e. not "I want to buy" but "I want him/her to buy".)