This is some advice to really consider. The biggest problem I would think is most of the cost is going to for the developer to figure out your brokers/data providers api. Even if you do pay up and they do a good job, if you want to switch data/brokers 2 years from now your stuck. Anyone of programs mentioned above already done the grunt work, unless there is something you want to do that those programs can't do you would be much better off looking on their forums and find someone who will write a script.
I think edvar (using excel, etc) is the proper way to start before you go spending money on custom development. Find out if your strategy make $ first. Usually you'll need custom development on your strategy when you want to increase your portfolio (ie: monitor a few 100-2000 equities)... First find out if your strategy works then get custome development done. Cutom development can get pricey. I do not think you need 10k to find a good developer, but $1k-2k will get you started to find the right developer for you. As anything else, if you are making money and you want more work done, then you are going to spend more on development. Get a developer that knows your API. Yes, a senior developer can learn a new API, but you will pay for the learning curve. That is not a bad thing if you have the budget for it. The worst thing is to get the wrong developer. Remember you pay what you get for. We have way to license the software to make sure we get paid. Beware of a developer is asking you for money in advanced (unless you are asking for a sh..load of work). First start with a small component here, and another one there. You will more likely get a componet (limited usage, etc) before you pay for it. If you want the source code make sure you specify it that upfront. It will probably cost you more with source code (unless you have sometype of long term businees agreement with the developer). Once you establish a relationship with the developer (and viceversa) and you feel confortable then your are good to go. Is a 2 way street. A developer will continue to work with you as long as you both are making money.