Please do not go the dongle route I was a user of wysiwyg from vr 3 and that darn dongle thing drove me crazy. I went to LDI to talk with the folks that make the product and get it to work as my one dongle stopped working and they were a no show to LDI. Very mad at them I see Lars and Capture talk to them and he says no dongle needed so I take a look at the student have a few others I work with also give it a look and bang we all buy in.
We use Vector Works for CAD as it is a Standard in use today but if runs over 3K to buy and well to keep up to date it is like $450 a year with Capture the updates are at no charge year to year (a plus in the bottom line) but if there is a charge from the Capture Team it is very low for users and is a major upgrade.
If you want to rent the software well find a shop in your area and rent it from them just like you would a lighting desk. We at Modern Lights have rented or even loaded our Laptop with Capture to other Lighting Designers and each time they have looked at making the investment into the software. We also have two Laptops with the student software on it that we have for the kids at a High School we assist in teaching. The kids take to it easy and as it come to the real shows well that is when we bring in our full vr of Capture and let the kids go for it.
Plus as I know Capture give us two seats for use and we have one Laptop and one Tower workstation. So you could invest in a good Laptop and a good Tower we did for about $4.5K in hardware.