What's gob smacking is the cost of a panel fit GPS. Now that IS eye watering.
One of the main reasons to use a tablet is that they are way cheaper than a panel mounted GPS.
And they are cheap compared to flying costs in general. For 1 or 2 hours rental rate you can buy everything you need. It reduces planning time and adds safety IMHO as it reduces workload and warns you of airspace changes (planned or accidental).