RIPE is the RIR with the most liberal transfer policies. In RIPE, legacy address blocks can be bought and sold (even partial blocks) without a needs-test and without the requirement that the recipient become a RIPE member or that the addresses lose their legacy status.
RIPE provides some services for market participants, including a list of recognized brokers and a list where buyers and sellers can post need and availability. RIPE also provides a log of all intraRIPE transfers and interregional RIPE transfers. IPTrading is a long-time recognized RIPE Broker.
IPTrading.com is also a RIPE LIR member and has access to the RIPE Transfer listing service, which is restricted to RIPE members only.
RIPE IP transfers can be tricky, with various requirements for the different types of addresses transferred. For example, PI transfers require an LIR sponsor, and as a RIPE LIR, IPTrading.com can assist in these cases.
RIPE addresses can be transferred to account holders at RIPE, ARIN, APNIC or LACNIC. RIPE does not charge any transfer fees, but it does restrict resale of nonLegacy transferred addresses for two years after the transfer.