Which saddle?

I`m 5.4 ...150lbs.....ok ok Im 155lbs
Which size saddle (english) and (western) do I need?
I swear Im either to dumb to meassure me or my hip bone keeps moving
How does it work here when buying a english saddle,I can only buy from catalog or used,how do I even know what kind saddle I need?(I either wanna buy a dressage and jumping or a "all in one")
How much should be a decent used saddle be?(english or western)? What to watch out for ?
Help?

Western: depends on your bum size (you have to try different ones to see what is most comfy)

English: bum size + thigh length. Here is calculator: English Saddle Seat Size Calculator

As for saddle itself - look for brands. It's better to get used nice brand than brand new crappy brand. You can also look into synthetic saddles: they are on cheaper side, but quite comfy. Do you own a horse? Because you really want to get a one that will fit your horse and your own back (and it's harder to fit an english saddle usually).

Regarding English saddles (I know nothing of Western):
If you're not on a budget, you have some wonderful saddles to choose from! If you're on a budget, it's far better to buy a less expensive used, good, name-brand saddle than buying an inexpensive new one. Get a quality saddle. A cheaply made saddle can easily hurt your horse and put you in a bad position. You can get good, used Passiers and Stübbens (I love the German saddles personally) for between $300 and $1000, depending on how old they are. Don't buy a no-name saddle - these will often be made in India or Pakistan and are sub-par quality. Some brands to look for off the top of my head are (both expensive and less expensive): Devoucoux, Beval, Passier, Courbette, Kloster Beim Schonthal, Crosby, Collegiate, Pessoa, Bates, Wintec, Thorowgood, County, Stübben, Thornhill, Kieffer, Hermes, etc. I know I've missed many. Stick with European and Australian made. You may find a good US or Canadian one as well. You can probably get some of these brands for as low as $200.

For seat size: sit in a chair with your knee at a 90° angle. Put a board behind your behind, so it sticks out to the side. Measure the length from the board to the front of your knee. The table below will give you an approximate seat size. Note that all saddles fit a little differently. Also note that if you're buying a used saddle, many people who advertise and list them have no idea how to measure the seat correctly, so they list the saddle as the wrong size. Seat size is measured from the center of the nailhead at the side of the pommel to the center of the cantle. Based on your height and weight, you'll probably be a 16.5" or 17" English seat size.

Up to 16 1/2" 15" seat
Up to 18 1/2" 16" seat
Up to 20" 16 1/2" seat
Up to 21 1/2" 17" seat
Up to 23" 17 1/2" seat
Up to 23" 18" seat

Sorry for the double-post. I saw you had more questions, and I wasn't fast enough to edit my post.
What to watch out for: Watch out for broken trees. A broken tree is a saddle death-sentence. For English, watch out for the condition of the panels. If they're hard or lumpy, you'll have a very unhappy horse. Make sure hte tree-width is correct for your horse's back and shoulders. Read the saddle-fitting section on this forum.
What kind: You say dressage or jumping or all purpose. Well, that pretty much covers most of the English saddles out there. You have to ask yourself what kind of riding you'll be doing, do you like a deep or flat seat? Do you like knee pads and blocks or do you like a plain flap. Do you like riding forward with your weight off the seat or sitting deep and upright. Can you try different types of saddles before buying something?

It sounds like a General Purpose/All Purpose/Eventing (all mean the same thing) saddle is what you are looking for.

The Collegiate Senior Event is a really good pick.

After reading everything(thank you all), I think it will be better if I look for an all purpose this way I will only have to worry once to find one who fits
I be riding basic dressage.lil jumping ,trail.

Was thinking about buying later on a western saddle for trail riding.

My Horse is on the lean side,he will have to gain muscle and a little weight....Whatever saddle I find now will I have to replace that one once he fills in?

Tough one. You have a few options:
-1- Get one that fits now. When he fills in, you'll probably need a different one. If you make sure you don't overpay for the one you get now, you should be able to sell it for close to what you pay.
-2- Get one that's a little wide now, and use shims or a correction pad to fill in the difference. When he fills in, it may (or may not) still fit him.
-3- Get something with an adjustable tree, like a Wintec with adjustable gullets. A lot of the newer saddles in other brands allow adjustment now as well. Note that the adjustable tree/gullet still doesn't guarantee that the saddle will fit, since there's more to saddle fit than just the tree angle or gullet width. But if you find one of these that fits nicely, it may likely adjust to fit nicely when he fills in as well.