Been buying parts from DE, NL, PL, CZ for the past couple of years...
Better prices by a long shot over IE and UK... and typically better selection of parts too (not Subaru specific, but across all brands in general both OEM and aftermarket).
Only thing is that shipping can be dear if only buying a single (lower cost item)... then again I have seen plenty of cases were for example a 80 euro part plus 30 euro shipping still ended up being 40-60 cheaper than buying at trade motor factor (with trade discount) here in Ireland. A lot of the mainland supplier have been stocking a good selection of RHD parts (where different from LHD) for at least two years now.
Recent examples:
1) Full kit for Volvo D5 top end (rocker arms, hydraulic tappets, all seals and gaskets, new glow plugs and glowplug connectors with wiring, injector fitment kits), plus 3 engine mounts, all bushings, droplinks, ball joints, bonnet and boot gas struts, all fluids (autobox, ps, oil, coolant, diffs) and filters, rear discs/drums, shoes and pads plus park brake cables... 1665 abroad... cheapest quote IE was 2175 and list was 2740.
2) Glowplug control module for a Qashqai 1.5dci, List IE 149, discounted 119 --> abroad 72 euro... same part same brand... but obviously plus 30 shipping. Normally shipping not a big deal as try order stuff together, but in this case was stuck for it, but still came out ahead by 17.
3) VAG pneumatic control unit (one box with solenoids which controls egr, boost, brake booster etc), eye-watering 349 from stealers, 289 from factors, 125 abroad... all original VAG OEM...
Look at the mental margins taken by suppliers here... and keep in mind the suppliers abroad are not the St Vincent de Paul either, and obviously are making a margin too, and yet there are substantial (almost unbelievable) savings to be had. Time wise... sometimes you can get stuff quicker here... but not always as there is F'all stock held in country, so from experience I can say that regularly you are as quick ordering abroad and sometimes even quicker. * Just make sure it is the right parts you order and double triple check, as you can of course exchange parts but would be on the hook for the return shipping in most cases.