No, I used sendfrom.

I wonder if the client forces the 0.0005 fee for sending a number of transactions in a small time frame. 

Not sure if this is what you mean but the txn was initiated only a few mins prior to appearing in the next block so I'd imagine the age is at most 1 or 2 out. The txn was added to the same block 68950 as the previous txn (f8187d) initiated from the same client.

As the subject says, is it possible for the bitcoind to operate with just public keys set either directly or through another tool (pywallet?) manipulating the wallet.dat file?

The client had a smaller fee of 0.00003 set using 'settxfee'. This was correctly applied to two earlier txns (08da53 and f8187d).

The bitcoind client used 0.0005 automatically for the txn in question.

It is not active yet but you can register your interest at BTC Xchange 

I'm using testnet and testing my understanding of txn fees and came across a txn that I would not expect a fee to be applied.

From https://en.bitcoin.it/wiki/Transaction_fees


Using the priority formula in the Technical Info section, I calculated the fees for tx e212c55 using the following information:

Input tx: adff686
Input amt: 399950000
Input age: (Tx e212c55 is in block 68950 - Tx adff686 in block 68414) = 536
Priority = 399950000 x 536 / 225 byte size = 952,769,777.77

This is greater than 57,600,000 priority so why did bitcoind enforce a tx fee of 0.0005? 

Limit orders usually set at a specific price or better.

Sell limit order @100 means "Sell at 100 or higher"

Buy limit order @100 means "Buy at 100 or lower"

Recommended quick start guide to trading terminology http://www.sec.gov/investor/alerts/trading101basics.pdf

Hope that helps

Not an immediate answer to your problem but we are in looking to rectify... Keep an eye on https://btcxchange.co.uk 

Hi-de-ho.

We're looking to help facilitate trading between buyers and sellers in the UK.

If you are interested please visit https://btcxchange.co.uk and we'll keep you up to date.

I operate in the UK and would look at your question from a different perspective. I wouldn't alter any of my accounting. Instead of selling an item with a price in bitcoins, keep it in GBP until the point of payment and then treat bitcoin as a payment mechanism like any other like a debit card, voucher, cheque etc. I'm assuming in the example below you are VAT registered.

You have a laptop to sell to someone in the UK worth £200 + VAT = £240. They also need a power cable at £5 + VAT = £6.

Total Net Value - £205
Total VAT - £41
Total - £246

Assume GBP/BTC rate is 1 BTC = £24.60. You accept 10 BTC to settle the invoice, transfer it to GBP and continue performing your accounting in GBP.

Hope that is of some help