Finding the right software designer for your needs is a real challenge. There are so many options. You can choose a large firm that has a wide variety of talents and
you can be pretty secure knowing that the project will complete but it could be pretty costly. A small to mid-size firm will be more price competitive and they may have a specialty that is close to your requirment. The disadvantage is they may not have the full spectrum of staff to cover the entire project or they may struggle to have the availability you need. Very small firms and individual contractors can be very price competitive but this comes with not having a broad skill set there will almost always be availability issues. Another concern with very small firms is who will support it after it is done.
Off-shore development can be very price competitive but is probably best left to companies that have the internal staff to manage and architect the solution and farm out the coding effort. These type of projects can be very challenging for the inexperienced
