Disappointing that no responses to date.
You could have a look at RF Solutions (UK). They do a lot of 433 and 868 stuff as well as Xbee type modules. I don't know if they have what you want. There are also the usual RS, Farnell and Digikey suppliers - I find that Digikey have the widest range of items. If the worst comes to the worst, it might be possible to find an adaptor for the surface mount. Like a lot of chip manufacturers, Digi are pulling out of the TH format, but many of their potential customers start life with prototypes in TH form.