While you can argue that Proto:87 is more than merely about wheels and track, but about a whole modeling philosophy, wheels and track are the hard bits. So, we offer the following sources for them

A.M.J.L

AMJL are making some of their new releases, such as their BB 66000, available in Proto:87

Apogée Vapeur

Sell fine kits of the golden age of steam in France, including locomotive wheels

AW-Cannstatt

Artisan who will and has produced Proto:87 trackwork

Club Proto 87

Club Proto 87 also offers some products

D.D.Wheelwrights

Wheel and gauge specialist for Proto:87 concentrating on the Dutch scene

Fast Tracks

Fast Tracks can supply their fixtures for Proto:87.

HP1

The hopur magazine

Lematec

Lematec started offering some of their brass locomotives in Proto:87 in 2010

Micro Metakit

Can anyone confirm if this manufacturer is offering anything in Proto:87? Post to the comments, please

Proto:87 Stores

Most everything Proto:87 can be bought here

Railflyer Model Prototypes

Offers some Proto:87 diesel wheels, and a very interesting drive mechanism

Railway Engineering

Railway Engineering will build Proto:87 turnouts to order

Wagenwerk

Has some Proto:87 wheels

Want one added? Post a comment.