If you've been wanting to try the Hourglass 1.5mm Mechanical Gel Eyeliner Pencil, the W7 Skinny Mini Black Micro Eyeliner looks like it could be a decent budget friendly alternative. I've tried quite a few things from Hourglass, but never one of their eyeliners. But their 1.5mm Mechanical Gel Eyeliner Pencil is popular due to how microscopic the nib is, making it ideal for lining the waterlines of the eyes. This eyeliner is just available in black, whereas the Hourglass liner is available in five different shades.
W7 Skinny Mini Black Micro Eyeliner
The W7 Skinny Mini Black Micro Eyeliner is £4.95 via the W7 UK website, but you might be able to find it a little cheaper on eBay. The description sounds almost identical to that of the Hourglass Eyeliner, except the nib on the W7 version is 1.7mm, and the Hourglass version is 1.5mm. Both versions claim to have a waterproof, gel formula that lasts.
Comparison wise, the Hourglass liner is £16 but the W7 Skinny Mini Black Micro Eyeliner is considerably cheaper at £4.95. I really want to try this pencil! I always line my eyes, as it makes my lashes look less pathetic, so the idea of a tiny nib being able to get between your lashes really appeals to me, and because it's retractable you never have to worry about sharpening it either.