Unfortunately the cost breakdown for the FP1 (available here) is far less detailed, and only mentions € 185 as product cost (which is stated as € 340 for FP2, but there is a difference between the two models whether things like the worker welfare fund are listed as project or as intervention, so difficult to compare).
The modular design will mean higher production costs (glueing everything onto one board is cheaper), which do not fall under development costs. However, it won't explain the full difference as assembly is an estimated €37.20.
Note that components may also be more expensive as the industry works in dollars, and since 2013 when the FP1 was being made, the Euro has lost somewhere between 15 and 20% of its value against the dollar. Based on the FP1 product being €185 originally, it would now be > €220*, due to the effect of currency value fluctuations alone (e.g. inflation is not taken into account). If we do assume a low inflation at 1%, costs in other parts of the breakdown of €15 that were actually in dollars, and a 20% VAT rate, the final price of the FP1 adjusted from 09/2013 (€325) to 09/2015 would be €377. Again, not the full difference, but it all adds up.
*Based on a September 2013 rate of € 1 = $ 1.34 and a September 2015 rate of € 1 = $ 1.12. The FP1 would now cost (185 * 1.34)/1.12 = € 221.34.