I have personally tried two different ways, and am aware of 3 ways possible:
1. Paint the whole thing with white enamel paint. Do a few coats. Sand between coats. The paint should be under $30. Then use a dry-wall framing square to make your gridlines in pencil. Sharpen the pencil before each pass along the grid. If your doing a table the size of mine, you are looking at drawing a lot of lines (mine is 8'x4'). This will likely take a long time but will also be your best looking table. I hope to return to this one soon.
2. Use the large presentation gridded paper, lay them down and cut to size. This will be ready for game play that same day. Disadvantage, the lines are really light. This is my current setup only until I can redo the other (painted) sides lines. I think those pads are rather pricey, around $30 for a pad of them.
3. Black thread and thumbtack method. As with option 1, paint the table white, but instead of using pencil to make your lines, take a spool of black thread and wrap around thumbtacks placed one inch apart on the sides of your table. Then do the other direction and if you did it right (e.g. everything square) you should have a grid when done. I haven't tried this but if you do, let me know your results... I am contemplating it.
Place a sheet of plexiglass on top and you are ready for gameplay. My 8'x4' plexi sheet cost me about $125. It's probably higher now. I also recommend buying two 4'x4' sheets as they are far easier to manage. The drawback of the plexiglass is scratches. Mine is only a year old and showing some scratches... probably hard to avoid. Oh, and purple dry erase doesn't seem to come off of it very well. I suggest just using Vis-a-vis markers.
One last thought about the ultimate gaming table. The way they do it is the expensive way and has a couple drawbacks. First, it's big... very big. Without the drawers you need to have 8' of clearance on the sides, with you need 10'. Second, the corners of the table aren't supported, and the table bows when someone leans on the corner. If I was to do it again I would do the 4x4 post method I saw in another recent post here on ENWorld.