I've used those kits at least a half dozen times successfully on multiple vehicles. Done carefully they work extremely, imo. In fact I've never had a crack get worse and require a windshield replacement after using the kit. I would try that before replacing a windshield you can't afford, OP.
In regards to the poster who said the repair kits don't work because if you push on the glass it will cause the crack to get worse.. uhm.. don't push on the glass!