I wholehardy suggest you to look at Don's variant (you'll find it in the
errata link on Don's signature), as it's far better than Merchant Prince (IMHO one of the worst changes Traveller made, and I'm still amazed that it was kept in the various versions until MgT).
Here's my oppinion about why it's not a good version:
http://www.travellerrpg.com/CotI/Discuss/showpost.php?p=403415&postcount=4
That is one reason why I questioned how many tons of speculative cargo are available. A buddy and I were looking at creating an ad-hoc set of rules for speculative cargo proceedures. The idea being:
A) There is the quick turnaround market where everyone and their second cousin are shilling cargoes at the market with quick access to/from spacers at the starport. These "bargains" will almost never be bargains simply because the crowd of available speculative personnel will always keep bidding up the value of the cargo until it reaches a point where it is barely profitable.
B) There is the no so quick turnaround market where you have to go off the beaten paths (and by beaten paths, we're talking about not using the electronic databases for ease of search by spacers - as that is what makes any cargo fall under the category of option A). As a consequence, the spacers have to engage in building relationships with the locals (adventuring material anyone?) and look for things that might not normally be construed as a resource. An example might be that of finding a person who wants to build custom grav vehicles, but doesn't have the initial cash outlay, or perhaps buying custom built grav vehicles from 5 people who compete against each other in the saturday night drag races. Another possibily is discovering a sweet sounding voice and convincing her/him/it to record its voice as entertainment media - then selling it. Perhaps it is a stand of alien trees that some local has finally figured out how to process that is relatively cheaper than standard costs.
C) Those once in a life time events where someone's business goes bankrupt and they have stock lying about to be snapped up. Or perhaps someone has control over a large amount of goods for a bankruptcy, but is willing to choose a speculator based upon how much kickback they can get without the general population knowing about it.
Finally? The better the merchant, the better they should be able to work the system. So the initial thought was:
Build three tables. Table A contains the barely profitable stuff. Table B contains the more profitable stuff, and table C contains the once in a lifetime stuff that rarely happens. So a fast turn around attempt on Table A might be geared towards a profit margin of barely 10%, an attempt on Table B might be capable of profits that are truly respectable, while Table C can only be rolled upon if one originally rolled on Table B and got a "roll on Table C" result.
The problem then, would be to determine how hard it is to find a speculative cargo lot worthy of the name, and how much. GURPS FAR TRADER's speculative rules provide too much pain for too little gain. Classic Traveller's Book 2 gives too much gain for too little pain. MERCHANT PRINCE (and subsequently MT) seemingly has a good idea, but lacks the limit of how much any one speculator can expect to find in a short period of time. Making the roll on the same order of magnitude for finding freight, seems short-sighted to me. Not putting specific wording (that I can find thus far) on what the limits are, seems to be an oversight.
Putting this in perspective? A while back, I was looking for miniature rules for fantasy gaming that was on a time scale I wished to use. I finally looked at Chivalry & Sorcery's miniature rules for second edition - only to discover with shock - they they were missing a chunk of rules required for resolving melee combats. It was as if a whole page of rules were missing. It turns out, no one had ever used the rules seriously. It looked nice, but no one actively put it through its paces before its author died - over a decade after the rules were printed! Likewise? It almost looks as if Merchant Prince looked nice, but few people really used it or perhaps few GM's looked at it with a jaundiced eye.
Overall? If speculation is to be supplementry to freight hauling, it should be less "common" than freight. If one is to build a company that does little BUT speculate, it should be somewhat time consuming and difficult to make one's fortune quickly. Staying on a planet for a month or two to get speculative cargo, and then barely making enough profit to cover the cost of expenses for a ship - serves the same purpose of the monthly grind of trying to cover costs with hauling freight and engaging in a little speculation to make up the difference. It gives the GM incentive to populate his market worlds more, and gives the players more incentive to stay on a world for a brief time trying to get cargo together - thereby allowing the GM to put into motion, some adventures.
