Car auction app

I am looking for experienced app developers to create an auction app for cars. This would act as a platform for anyone looking to buy or sell cars. The platform must be developed for both iOS and Android. I do not have an existing database of cars, so this must be created from scratch. Finally, the app should include open bid auctions, giving users the opportunity to bid for their desired car. I need this in 6 months max and must also be made in Flutter flow. I have the proposal file downloaded that has all of the needed information, it's attached.