IMHO building from ground up is better in long run. Unless you find something that will not run you into limitations with your current goal and is flexible enough for future plans. If you find some ready made software that is open source and you understand its flexibility and inner functioning its also good. I have been working on various automated trading algos and i dont know my future plans , but so far i would have run into limitations with almost all ready made trading software platforms.
Upwork has plenty of useless "I can do anything" types as well. Reviews don't always reflect that. Also, you're tied to Upworks terms and conditions. Might as well find someone here but yes, OP needs to post actual rates and requirements. For now there's no clarity.
How did you migrate a strategy in Easylanguge to sigma trader? Is there a conversation programs or you had to write same codes in C# or phyton over again. Is sigmatrader can be used by non programmers ?
SigmaTrader is C# based so the migration required coding. SigmaTrader does have a discretionary desktop feature any algos need to be coded.
How does sigmaTrader compare to quantopian and quantconnect? Why is there a need for another backtesting platform?
You should post overview of what you plan and limitations like budget and timeframe. I have some experience with various historical data and market apis but have not yet combined any api client and algotrading core into single software. It might be additional cost and complications at beginning but later if you decide to swap platform its better. IB api bridge--software Ninjatrader--NT bridge--software MT4/5 terminal/s with MQL4/5 bridges--MT bridge--software "software" has single code to com to all and "bridge for IB api" can run in virtual machine or seperate computer and needs 1 networking port open in firewall. The bridge is single app atm as i have some UI stuff with statistics also and dont want to keep 3 projects up to date.
I was lucky then as I found an expert in NT7 and NT8. The last 5 years he did several jobs for me. He is even writing as subcontractor for vendors that are on Ninjatrader. I know an ET member that used him too. And he is not charging $200 an hour.