Offers are being made to purchase claims based on the claim’s approved JPY value. The trustee valued every claim based on (a) the price of bitcoin at the time MtGox went into liquidation (roughly $438 USD) and (b) the conversion from USD to JPY. Purchasers are offering a percentage of this value for claims.
For example, if you held ten bitcoins in your MtGox account you would now have a claim worth approximately USD $4,380. You would not have a claim worth over USD $10,000, the value of ten bitcoins at the current price. If a purchaser offered X percent to buy this claim, the offer is for X percent of $4,380.
There is a misconception among some creditors who held bitcoin balances at MtGox about the meaning of “bitcoins may be returned as bitcoins”. The trustee did indicate that creditors may be paid out in bitcoins, but this has nothing to do with how the value of a claim has been calculated. Your bitcoins were assigned a value by the trustee and this is all the claim is worth. You may be permitted to receive this value in bitcoins, though how this would happen has not been worked out.