Lotus remain in the throes of resolving their financial future, a problem that resulted in Kimi Raikkonen opting to return to Ferrari on a two-year deal from 2014.
It also appears to be resulting in a delay when it comes to Boullier naming his replacement as he is urging all candidates to be patient.
Sauber's Nico Hulkenberg and Felipe Massa, whose seat Raikkonen has taken after an eight-year spell at Maranello, are the main names in the frame, although not the only ones under consideration.
Boullier has again made it clear, though, there is no pre-requisite for his driver to come laden with sponsorship cash.
"When it comes to drivers we are not simply looking for a short-term replacement for Kimi - we are looking at where we are going to be in the next five years," said Boullier.
"We can afford to be patient, to ask the candidates to wait as we formulate our strategy for the coming years.
"I hope we do not have to take into account commercial considerations when making decisions on drivers because we have worked hard to build our financial strength without having to rely on sponsorship from a driver.
"We want the strongest line-up possible to continue the progress made in recent seasons - that is the priority."
Romain Grosjean is almost certainly on course for a new deal having impressed Boullier of late, and should he continue to do so over the final six races, starting in Korea on Sunday.
The driver banned for a race last season after causing a string of crashes would appear to no longer be on the scene.
Boullier added: "With Kimi leaving at the end of the year, Romain knows he has the possibility to build the team up more around himself.
"If you look at the last five races, he has done a great job.
"Since Germany everybody has noticed he has clearly 'switched on' and you can see the highs in every race.
"Whether we've been fighting for the podium or struggling a little bit, Romain has clearly been matching Kimi's performances, which is no small achievement when you consider the world championship-winning calibre of his team-mate.
"The Romain of the last two months is the one we all believed he would become, and I hope he keeps improving.
"If he continues in this way, it means he is 'on it' and delivering the results we all know he is capable of, which is very positive for his prospects in 2014."
Raikkonen, meanwhile, is to play it by ear as to whether he competes in Mokpo this weekend after coming close to pulling out of the last race in Singapore with a back problem.
"It's better than it was on Saturday in Singapore which is when it didn't feel too good," said Raikkonen.
"It's not the first time I've had a problem as there have been some issues with my back for a long time.
"We will have to see how it is when I get out on track on Friday."