Depends on buyer trust. All transactions on paypal MUST use the Gift option located under the "Personal" tab. If someone fails to do that, I press Refund, and the funds are returned minus the paypal fees due to the users inability to comply with the rules of exchange.
Paypal transactions are a bit above current spot tallied into the total transaction total.
Buyer wants 25 btc. Sends pm.
I reply with a quote for 25btc as bulk item.
Then send funds over, I send them a MtGoxBTC code to the email they sent the funds from dirrectly from MtGox.
If buyer wants a wallet2wallet transaction, the total cost will be slightly higher.
Total fees are cents in total. A transaction for 25 btc if btc current value was 5.00 would be 130usd or so depending on method of demand.
Western Union rules are pretty much the same. I will buy/sell via Western Union. Hours will vary as availability to WU may be limited during specific hours. If it is late here, I will still process your order, but this is the only time where I will charge a higher premium as I have to wake up, and drive far.
A WU Sell requires coins to be sent in first or MtGox USD/BTC codes. Wallet2Wallet locks in price at 6 confirms, Codes are at rate. Seller pays assumes WU fees which are calculated and subtracted from the sale price.
A WU Buy requires funds sent to me exactly as information is sent to you. Any denial by WU for incorrect name, or other info will not reimburse you for lost WU fees. Once MTCN is sent and funds are revived, the btc will be sent via email in MtGoxBTC code or Wallet2Wallet.
Any and all fees are the respectability of you in the matters of Western Union. If fees are added into your transaction by WU and the total amount sent is varied, the transaction will carry out based on a ratio of FundsReceived / FundsRequested = Btc. If Jane is to buy $100usd of btc, and somehow only $90usd is received, she will be sent 9/10ths the agreed btc.
Feel free to ask any more questions. If I dont respond to your pm right away, I will get to you shortly.