Its not really a case of budgets, when I started i didn't have the money to go testing every week (still don't)
I bet if you paid one of the chassis builders in the UK the equivalent cost of that piece of software for an hour of their time, described exactly what you are trying to achieve, the weight of the car, type of suspension, type and size of tyres, rear axle etc etc the advice you'd get would be worth a lot more than the cost.
I've tried some of those software packages in the past and while they might give you a 'rough' guide to what you may be able to expect, they rarely, if ever, have the infinite list of real world variables you need to make the right decision, any one of which can push you off the edge of the track. Just a suggestion.