Here's an example of how overpriced the altcoins are when buying.

Convert 2.0 BTC to LTC

1. Sell 0.00000047 BTC for 0.00001333 LTC (price 0.03500000)
2. Sell 0.10000000 BTC for 1.0 LTC (price 0.10000000)
3. Sell 0.50000000 BTC for 0.50000000 LTC (price 1.00000000)
3. Sell 0.99999953 BTC for 0.499999765 LTC (price 2.00000000)  (yes... it costs 2 BTC to buy 1 LTC!!)

On pmtocoins, 2.0 BTC = 2.000013095 LTC

On Vircurex, 2.0 BTC = 77.40051458 LTC
On Cryptsy, 2.0 BTC = 77.59941812 LTC
On BTC-E, 2.0 BTC = 77.54467754 LTC

So to "withdraw" your 2.0 BTC via conversion to LTC on pmtcoins, then conversion back to BTC on another exchange, will net you about 0.05 BTC. That's only 2.5% of your original balance, a loss of 97.5%