Hello,
It does make sense - more expertise at same cost or less cost at same expertise. Of course, to avoid bad expertise at good price, that makes less sense :)
Regarding posted description, too soon for any conclusion, can be something simple or very complex. Most complexity could derive for example from the needs to extend the back testing/optimization/simulated trading outside what the platform provides, if are such needs. So an exact estimate could be after exact requirements. Regarding that, if not big direct projects(not the case for this I think), personally I prefer fixed projects, and worth to consider that way too if you know exactly what you need, more clear if specifications exact like x,y,z needed, fixed time of delivery, and fixed agreed price.
Few words regarding me: I will not insist on technical(you can ask any details needed), just to mention that C# is my main developing language and the one I am most productive in, and as you probably know, entire Ninja Trader platform is centered around C#/.NET (is developed in it, scripts run using it, most extending parts are done in it). Regarding trading:
I did work in past for traders and few small brokers, custom feed connectors, custom charting, some FIX connectors, use of platforms API's, etc. I did some simple trading scripts too, but most work was with a little more advanced tasks. As for platforms, did programming with most common used by retail traders: Ninja, MT4/5, TWS/IB API, TS, MC, etc