In his search for the extra quality he knows his side needs, the Celtic net has been cast all around the world.
No sooner do you discover a market where the quality is good enough and the prices and wage demands are low enough, but everyone else latches on to it and the targets rocket out of your reach.
So, it is a constant challenge to find the next country where you can get what you want at the price you can afford to pay.
Just look at the current United Nations squad and the last few days' headlines for proof of how comprehensive the search has become.
Celtic have had a midfielder from Japan on trial, Hiroki Yamada, and Neil has been over to Holland where it is reported he was looking again at Iceland striker, Alfred Finnbogason and an American front man, Aron Johannsson.
Then there's the link to Huddersfield's James Vaughan and Dundee United's Stuart Armstrong. You don't get much more diverse than that lot. But, will any of them end up at Parkhead? That's the $64,000 question.
When he took over as manager, Neil did a fair bit of business in the English Championship, signing Joe Ledley, Adam Matthews, Gary Hooper, Kris Commons and Kelvin Wilson, who all become key players in his team.
He was back down there looking again the other week, but that really has become a difficult market for Celtic as values have risen so much and wages with them.
Finding another Hooper would be the dream, but that's a lot easier said than done - especially for £2.4million.
It's also harder to get good value in the January window than it is during the summer, though Commons is an obvious example of how it can pay off.
Clubs tend to price their players higher in this window, perhaps in the belief anyone who wants to buy is under a bit of pressure to do so mid-season.
In actual fact, Celtic don't need any new players to help them retain the title.
However, with the Champions League qualifiers coming round so early in the summer, they would prefer to get new faces in now to give them plenty of time to settle into the side before these vital games.
Celtic's other problem is that the players they want to recruit - a goalscorer and a creative midfielder - always come at a premium price because of what they bring to a team.
That brings me back to what I have been saying for several weeks now, that the club must be prepared to go the extra mile with a transfer fee and wages when the need arises.
I'm wary of destroying the harmony of a dressing room by introducing a player on a higher wage than anyone else.
But, look at Liverpool. When they decided to hand Luis Suarez a bumper new contract, do you really think the likes of Jordan Henderson would have had a case for going to the manager and demanding a rise?
Of course not. Certain players simply bring more to the team, and everyone benefits from it.
Having said all that, I know Celtic can't compete with the really rich clubs, so it comes back down to doing the best with what you can afford.
Holland is a key market for Celtic, and there's no doubt Virgil van Dijk has proved to be excellent value for money, even if Derk Boerrigter has yet to do the same.
However, while the transfer fees there can be within their reach - though the money being asked by Finnbogason does appear to be a little beyond the valuation put on him by some within Celtic - you always have to look at the entire package.
That means multiplying the wages by the number of years the contract will run, and that can come to a lot of cash.
It might be cheaper to look even further afield, as Celtic have done in the recent past with Ki Sung-Yueng from South Korea and Shunsuke Nakamura and Koki Mizuno from Japan.
However, any signing from these countries must be for purely football reasons.
I don't really think Celtic made any real inroads into the commercial market there during Naka's time with the club.
In fact, I'd wager Naka's goal against Manchester United to put Celtic into the last 16 of the Champions League brought more cash to the club than anything they did commercially with him.
So, if Hiroki Yamada is to be offered a contract after training for a week at Lennoxtown, it has to be because of what he can bring to the squad, not the jersey sales.
With adjusting to a new country always a gamble, it's obviously a safer bet to look inwards for investment in players, and the young lads at Dundee United have certainly shown there is potential here.
The likes of Armstrong, Ryan Gauld, John Souttar and Andrew Robertson have caught the eye of plenty of clubs, and surely, if they really wanted to bring them to Parkhead, Celtic could offer them a significant wage increase and a step up in terms of Champions League football?
That would keep the money within the Scottish game, and, just as importantly, this talent within our league.
Ultimately, Celtic want to be producing and developing their own young players, like James Forrest, and put a lot of money into doing this.
But that's no reason not to look seriously at the best other clubs have managed to unearth - a rule that applies to talent all over the world.