If you let it lapse for less than 3 months, the extra training requirement might be 0 - the regulation explicitly says so. But it needs to go through an ATO and their HT approve it. If expired more than three months - with your experience level - the re-newal would be more expensive compared to keeping it valid.
1200 EUR for 2 hrs with TRE included sounds fair, prices are not much lower than that on the open market.