Seeing as I'm completely reconstructing my own MLB model this year, I took some time over the last couple of days to build the model described in Justin7's book from scratch, just to give it a look, using only Excel with:
- Player data from Sports Prospectus
- Park Factors from ESPN
- Projected rosters from mlbdepthcharts.com (you can find them a lot of places)
Admittedly, I have experience building models in the past and solid Excel skills, but the most complicated functions you need to use are the HLookup/VLookup and Sumifs functions, and I feel like anyone with even midrange Excel skills can build this in a couple of days at most. For the moment, it really doesn't matter if your data is being updated daily from web sources. Regular season games don't even start for 6 weeks, so just don't worry about the data collection side of this for the moment. It's far more important for you to focus on the actual model building process (the part that actually does the calculations), and develop an understanding of exactly what data you need and how important/sensitive different stats are to the success of the model.