Hi! I am writing in English because my Czech is very weak

Sorry. If you understand you can answer even in Czech - I will understand.
I will get straight to the point.
I live in CR for more than 3 years. I am going to set up a small business (trade licence) - volne zivnosti / 48. velkoobchod a maloobchod.
I would like to be \"neplatce DPH\" and buy good quality goods from Germany, Hungary, Poland and sell them through Aukro.cz.
I know that when I buy in other EU countries I will get 0% VAT-EU (<326 k Kc per year).
Let\'s say I will buy mp3 player for 100 EUR (~2500 Kc )- this will be the price on the invoice VAT-EU 0%.
What should be the price in Aukro auction? Let\'s say I would like to have 30% of margin. Should I sell for 3250 Kc (2500+30%) or for 2500Kc+ DPH20% + 30% margin ? Should I add DPH 20%?
Next thing - how to put cost of \"Doprava\" on my invoice to the end customer? Lets\'s say I will be selling MP3 player for 3500Kc with \"doprava\" on Aukro - \"doporucena zasilka 39Kc\". I will get on my bank account 3539Kc. What should I write on invoice (doklad pro zakaznika)?
Pozice 1. \"MP3 player\" 3500 Kc
Pozice 2. \"Doprava Ceskou Postou\" 39 Kc
?
It could be great if you could answer my questions.
S pozdravem!
Joe
p.s. portal jakpodnikat.cz is great!
