The company has so far raised almost £790,000 from 359 investors with 21 days remaining of its funding drive.
The group, which has four London locations, is planning to use the investment to open further restaurants. It says it is negotiating on a site in the new Southbank Place office development near Waterloo.
It says the location is just under 200m2, slightly smaller than its Nova Victoria location, and features outdoor seating.
In an update on its Crowdcube page Sourced Market says it expects to open the site in late spring 2019, if the lease is secured.
Sourced Market originally launched the crowdfunding campaign to support plans to open a potential site in Eurostar Departures Lounge, and a location in Holborn with its hotel partner.
It also intends to use the funding to develop an airport model, working with a franchise partner, increase kitchen production capacity and make key personnel hires.
Sourced Market started trading as a music festival pop-up in 2007 and now has four London locations in Victoria, St Pancras station, Marylebone and Barbican.
It reported turnover of £6.4m in the year to the end of April 2018, with a £888,000 EBITDA loss.