Are you planning on buying new? You can get a lot more bang for you buck on the used market. An important thing to keep in mind when using more than one cab is the minimum impedance (Ohms) that your head is rated for. If you have a head that is stable at 4 Ohms minimum, then your options are to use one 4 Ohm cab at a time, or you can use one 8 Ohm or two 8 Ohm cabs at one time. There wont be a huge difference between the volume of a 4 Ohm stable head into one 4 Ohm 410 versus that same head combined with one 8 Ohm 410, you will have a bit more head room with the 4 Ohm, but you dont loose too much volume.
For my money I would find a head used in the 300-500 wattage range, and then find a cab that I could double up on with my head.
As an example: If I found a Peavey Mark VIII XP (I have one) I would have a lot of options as it will run just fine at 8, 4, or 2 ohms. I could start with one 8 Ohm cab and add second matching cab later (or maybe a third if I need to be loud). I could also start with one 4 Ohm cab and add a second matching cab, but if I ever wanted to change my head my options would be limited because of my cabs.
If I found a used Ampeg PF-500 (I also have one of these) I would defiantly want to start with an 8 Ohm cab, as it is only 4 Ohm stable. Fortunately there are tons of great options in 8 Ohm cabs. For my preference I would go find an 8 Ohm 115 cab, then down the line I would pick up a second matching 115 cab for a nice little stack.