Seeker Toolbox as Firefox Plugin
Not ideal, but interesting, as it's an implementation that reduces the dependency on crawlers (which are complicated from a totally distributed seeker perspective) and/or third party warehouses of pointers to seeker and vendor data store locations.
Vendors may tag pages with Technorati-style information: href="locationToVendorAgentOrDataStore" rel="VRM"
Seekers install browser plugin and configure with basic information (private identity, location of public identity, default behaviors). When the seeker visits a page that's tagged with VRM information, that information is either automatically or manually (user option) to their data store. RFP creation can then be handled locally, from within the browser (online or offline), and the RFPs passed to vendors when a network connection becomes available. Plugin could also periodically poll known vendor data stores for offers that match the user's outstanding RFPs.
Could work bi-directionally, as well, offering user the option to submit their own data store information (if they have a public location for RFPs, which becomes optional in this model) to individual vendors, who then periodically poll the user's public RFP.
This approach also fits with third-party participation, as third parties can act as aggregators: visit aggregator site and get data store information for 10, 100, or 1000 vendors all at once if desired. Conversely, user could submit their public RFP location to 10,100, or 1000 vendors all at once.