You'll be surprised at how far a good set of metric allen wrenches will take you. My next purchase would be a cable cutter and I'd step up to get a good one because it's a frequently used tool. Insted of trying to buy everything at once, I'd suggest getting a few tools that you need immediately but buy quality.

Beyond that I'd buy specialty tools as I needed them. Multi tools are handy on the road, but I think that individual tools are better for home shop use. For example, a simple job like installing a water bottle cage can become an exercise in frustration if all you have is a bulky multi tool.