Having just experienced a headgasket failure, I have a few thoughts for you:
1. The indepedent LR shop here wanted $1800 for the job. (The dealer was more) $1300 is a bit low - look out for non-genuine parts.
2. Most likely the dealership wants to do a compression test. The equipment required to do one yourself is around $30. The process is simple. If that's all they are doing for $106 - do it yourself.
3. If there is no intermixing of oil and coolant, or no adjacent cylinders are low on pressure, the head gasket can still be blown. Diagnosing that can be a bit of
Good luck!