Accounting System in C# using SQL Server

I am looking for an existing C# Win forms accounting system I can integrate into a custom retail optimization system. I wish to purchase mainly exiting source code, but some modifications are expected to achieve the requirements. Must be written in C# with SQL Server 2008 or 2012 database. Prefer MVC model for code and very little, if any, in-line SQL. Must be up to framework 3.5 as a minimum. Bidders must provide screen shots of proposed solution. Those not providing screen shots will not be considered. Use of third party controls okay as long as reputable. General overview of accounting features: A) Core Accounting (general ledger, financial reporting, accounts payable and accounts receivable, Sales Order processing, inventory, Trial balance, system side reporting for each area). B) Bank reconciliation and reconciliation of balance accounts in general C) Fixed asset management D) Multi-currency and Multi-language E) Chart of accounts must support roll up of sub accounts F) Inventory must handle LIFO, FIFO, and WAC inventory valuation methods.