Too bad you didn't post this a week or two ago, Best Buy had a deal on a sweet Lenovo Yoga machine with an i7, solid state, and dedicated graphics for under $800 after a $150 student discount. All gone now, unfortunately.
If your goal is running Solidworks, you're going to want a dedicated graphics card. The standard integrated graphics on most laptops is inadequate for this, while it might run the program, the performance will be sub-par and manipulating objects will be laggy.
Looks like HP is running a pretty good deal on their
Pavilion 15t laptop starting at around $600, the base specs are:
i5-6300HQ Processor
Nvidia GTX 950M (2GB Dedicated) Graphics Card
8GB DDR4 RAM (uses 1 of 2 available slots)
15.6" 1080p Display
1TB 7200 rpm HDD (this is unusual, most laptops have the slower 5400rpm drives)
Whats nice is that it looks like you can upgrade not only the RAM and the HDD, but you can also drop in an M.2 SSD IN ADDITION TO the HDD (for most laptops it's one or the other).
The only other thing I might recommend is if you were going to buy one of these, spend a little extra and upgrade the CPU and/or Graphics cards in the config, since those are really the only key components you can't change after the fact (as they usually get soldered onto the circuit board during assembly). Don't bother upgrading the RAM or HDD over the defaults , or adding an SSD in the config process, they are MUCH cheaper to buy elsewhere and install yourself later.
It is a bigger screen than what you're looking for at 15.6", but typically when you go smaller on screen size you loose customizability and increase cost.
I can't speak to the durability of this model in particular other than to say that I have one very similar to it that has held up pretty well for the last few years (and using it for a similar application as you too).
The only other thing I'll say is if you're looking for durability, avoid "Ultrabooks" (super-thin laptops, usually with touchscreens) like the plague.