A few points; apologies for the chronology, it's just easier to reference:
1. Laminated glass is not repaired with any kind of glue.
2. The chances are, that anyone charging 20-quid can't be taking the job seriously. Whilst some repairs are much easier than others, an accomplished and experienced repairer - doing the job correctly - will not be giving it away like that. Not in my opinion.
3. There is a huge misconception on what a good repair is. So many 'incomplete', or poorly finished repairs are being presented/sold as good or acceptable.
4. Drilling requires training. if you don't know which way to drill, how deep - or at what angle - to drill, or if you should be drilling at all, DO NOT use a drill on your windscreen.
