The four that I have used throughout the last 2 years are:
Talika Lipocils (expert) $425 (340@sasa)
Trendaholic Eyelash Serum ~$220
DHC Eyelash Tonic ~$130
L'Oreal Renewal Lash Serum $80
1) Talika Lipocils (expert) - Made in France - 10ml
I actually repurchased this one. Before I was using the normal Talika lipocils, but they came out with this 'expert' version last year and from reviews I have seen, people say the only difference is that there is the new tip on the applicator. I'll have to test it out myself to see if it's true. Either way, the formula still beats all the other three in my opinion. So what Lipocil claims is that it helps lash growth by 36%, intensify lash color by 50%, and increase lash curve by 50%. I won't be able to tell you whether or not the statistics actually prove itself correct, but it definitely does do all three of it to some extent. What I like about this serum is that it isn't greasy and perfectly fine to put mascara on top of it. My lashes fall out significantly less when I take off my eye makeup - this I can really I swear by. For as long as the tube lasted (about 8 months), probably only about 3 fell out during makeup removal. It really is that good.
This is the applicator. As mentioned before, the sponge top is only for the 'expert' version, which is about HKD95 more expensive than the original lipocil. Honestly, I probably wouldn't pay that price just for the applicator, but I wanted to try the expert because the original one worked really well for me, so I'm hoping the 'expert' would help fill in my eyelash gap that I have now...
2) Trendaholic Eyelash Serum - Made in Japan
I got this one at city'super/log-on for about HKD220. The applicator of this one is just a sponge tip without a brush. It works well for getting to the roots of the eyelashes and also on the eyelashes itself, but it picks up a lot of product so I only used this at night and not in the morning when I needed to put on mascara. Even using it just once a day, this product was very good for promoting new lash growth, and also helped strengthen my eyelashes. In terms of length and volume increase though, it was not as apparent as Talika.
3) DHC Eyelash Tonic - 6.5 ml
This product has very high ratings in Asia. I've heard many people talk about it, and how effective it is. I must admit it's not bad, and definitely worth the price. The applicator is probably the worse aspect of it. It's a fiber brush that doesn't pick up much product so you have to be patient and put on a several coats. It did come to an advantage in the morning though, because a thin coat of this underneath mascara works quite well for holding curls (make sure you let it dry a little first before applying mascara). The formula is good for lash grow both in length and promoting new ones. My eyelashes didn't get thicker and darker with this product though.
4) L'Oreal Renewal Lash Serum - Made in China
Sometimes people save the best for last, but not me! This product did not work well for me at all. My eyelashes were so droopy after using it. The formula is very thick, and once you apply it on, it weighs down the lashes. After it dries, it also leaves a lot of residue. It did not promote any new lash growth, nor did it help improve the existing eyelashes. At first I thought maybe it was because I didn't give it enough time, but I've used it for about 4 weeks now, and still nothing. Usually these eyelash serums take 2 weeks for results, and I gave it double the time. There is one positive thing I can say about it though, the weird rubber applicator was surprising good.
So to sum up everything: you get what you pay for. Of course these are all just my own opinions and how the products worked for me may be different for others. I definitely recommend the Talika Lipocil, and for someone that is looking for a cheaper alternative, then the DHC Eyelash Tonic.