This whole sorry tale reminds me of the Martin Offiah saga... dummy spitting & toy throwing at its sickening worst.

What were Cas Tigers offered prior to him walking away ?

I'm all for player welfare and clubs honouring contracts but with Sandow and now Solomona it shows that some players don't feel they need to reciprocate it.

As a Salford supporter I've seen my club done over a couple of times by selfish individuals such as Australian Hudson Smith being released early from a contract on grounds on home sickness only for him to sign for Bradford Bulls on a free days after. I also recall us signing Schuster from Newcastle Knights only for him to change his mind weeks after putting pen to paper. The big question is are contracts more favoured to players than the clubs and do they need to be looked at to protect the welfare of the clubs as well? Where does this leave Warrington and Castleford now? If they would have known a few months back they would of had more time to find suitable replacements.

It is not an easy process.
However, there is an ace in the pack. Castleford received three offers for Solomona, which will clearly give an indication of his value to an employment tribunal. The fact that Castleford rejected them show they believe him to have a higher value than the offers made, but there is concrete evidence that he was a financial asset to the club that has been lost through his breach of contract.
Another element of financial loss is the increase in his salary when he signed a new deal in 2015. This would not have been offered without him agreeing to extend his contract to 2018, which he has now breached (it seems). Castleford have every right to claim the increase in salary should be considered a financial loss in these circumstances.
As you say, sponsorship is harder to put a value on. The club could claim the loss of direct player sponsorship (each individual player is sponsored per season) using last year's figures and the fact that Castleford had a sponsor agreed for Solomona next year for a higher price, which the club will now lose. Other than that, it's more or less impossible to put a price on the financial gains an individual player brings to the club.
If Solomona is found in breach of contract, I would imagine Castleford will claim for costs. This will be another substantial amount if Castleford are awarded these.
In his position, I would be worried. I doubt he has the finances to cover the money that Castleford may be seeking.

I think both Warrington and Castleford need to make an example of these mercenaries to deter other players from doing the same in the future.

Warrington have a harder job in proving financial loss as nobody was offering money for Sandow.
They can claim loss of direct sponsorship, but other than that I think they are pretty much powerless.
The RFL need to make examples of players who are found to be in breach of contract by preventing them returning to RFL competitions.

I think it would have to be a worldwide ban from the sport at any level. Additionally the International sports governing body could make it mandatory in all new player contracts for 'breach of contract' players to pay the club the sum of his remaining contract, as a penalty compensation payment.

The difficulty is that sport is professional.
So just like any other employee they are free to walk out on any terms of employment, just like any other employee.

The difference is that if I walk out on my job tomorrow getting a reference in future will be tricky.
Sports stars use their talent as their reference so this is not an issue for them.

The difference is sport whilst professional still markets itself by club loyalty and local-ism.

There are solutions but in a competitive market place they can still be busted by competitors.

i.e. Any wages offered 50% could be held in trust upon completion of a contract, a bit like bankers bonuses some of which are now paid based on performance 2 - 3 years later, to stop short term thinking.

However, this would need to be agreed across all SL clubs and as soon as one says they will only with hold 40% or 30% it becomes a race to the bottom.
Also clubs with more money could still offer to compensate any player for the loss of the end of contract bonus. So it would be a deterant but not a silver bullet.

The value of the transfer fee, Merchandising and ticket sales. Leeds claimed £3.2m for Harris.

But you aren't free to walk out on the terms of your contract. Your contract likely contains the terms for ending it for both parties. But if you don't follow those terms you are liable, similarly if your employer doesn't follow the terms for ending the contract they would be liable.

Without intending to be insulting, most people aren't important enough to an important enough business for those terms to be anything other than the standard 4 weeks notice and even if you broke them its not really worth taking action for, but if you were the CEO of Tesco, or an executive at Goldman Sachs however, your terms will be a lot more complex and they would almost certainly be problems for you if simply sent your resignation to Joanne in HR and then rocked up a month later at Asda or JPMC

Shouldn't this post be on the Bradford in Administration thread?

It must be bitter / sweet knowing your club's actions helped with Bradford's demise.

Winning the Harris battle yet losing your favorite games of the year.